Good morning to you all, and thanks for joining us on our call following the release of our 2021 results. I am with you, Jonathan Timmis, our CFO, and Denis Moreau, our VP of Investor Relations. I'd like to start our call today recognizing all of my colleagues around the world at Intertek for having delivered a superb performance in 2021. Indeed, 2021 marks the 7th consecutive year of group earnings being in line or above expectations. Our consistent performance delivery demonstrates the strengths of our differentiated ATIC value proposition, the science-based customer excellence of our organization, our unique performance management approach, and of course, the quality of our earnings model. They bring sustainable growth and value for all stakeholders. In our call today, there are essentially three takeaways. First, we've made strong progress in the second half, delivering broad-based like-for-like revenue growth with profitability ahead of 2019.
Second, we expect the industry to grow faster post-COVID-19, and we are very well-positioned to benefit from our current increased investments in risk-based quality assurance. Thirdly, we enter 2022 with confidence, targeting robust like-for-like revenue growth at constant rates, with margin progression and strong cash generation. Let's start with our performance highlights. In 2021, we've delivered a strong performance at constant rates in revenue, earnings and ROIC. Group revenue was GBP 2,786.3 million, up 6.5% year-over-year. Like-for-like revenue was up 5.6%. Operating profit was GBP 473.9 million, up 15.4%. Operating margin was 17%, up 130 basis points year-over-year. ROIC was strong at 18.2%, and our organic ROIC was excellent, at 24.4%, up 350 basis points year-over-year.
We've announced the full- year dividend of 105.8p, in line with our dividend in 2019 and 2020. As I said earlier, in H2, we benefited from a strong momentum and delivered a broad-based like-for-like revenue growth within each of our three divisions, delivering mid-single digits like-for-like revenue growth at constant rates. Let's now look at our performance compared to 2019. Our strong performance in H2 enabled us to deliver a full- year margin of 17%, only 50 basis points below our industry leading operating margin of 17.5% delivered in 2019. In the second half, our group like-for-like revenue was in line with 2019, while our profit and margin were above 2019. In our product division, we delivered a like-for-like revenue, operating profit and margin ahead of 2019 for the full- year of 2021.
We've continued to make great progress on cash management. We've reduced our negative working capital further with a cash conversion of 132%. Cash generated from operations was GBP 696 million, and adjusted free cash flow was strong at GBP 402 million. We've closed the year with a robust balance sheet. Our net debt to Adjusted EBITDA ratio was 1.1, higher than last year as we continue to invest in growth through the acquisitions of SAI and JLA. Let me take a few minutes to reflect on these two strategic acquisitions. SAI Global Assurance is a very exciting move for Intertek. We are scaling up our leading assurance business at a time where the ATIC industry is expected to grow faster post-COVID-19.
As you all know, assurance is a capital light, high growth and high margin service, which is mission critical to addressing the increased corporate focus on risk. The strategic fit of the SAI Global Assurance portfolio with Intertek is excellent, both from an excellent geographic complementary standpoint and service standpoint. Geographically, it strengthen our scale position in Australia, the U.S., Canada, U.K. and China. In terms of service, it expands our audit offering in the high-growth sectors of food, agriculture, quick service restaurants, sustainability and global market access. The integration of SAI is progressing well, and we are on track to deliver the expected revenue and cost synergies in the next few years. JLA expands our existing food and agri capabilities in LATAM.
JLA was established in 1990 and is a food, agri and environmental testing business with a strong track record of organic expansion. JLA enables us to enter the food testing market in Brazil, one of the largest exporter of agri-food products in the world. I will now hand over to Jonathan to take you through the financials.
Thank you, André. In summary, in 2021, the group delivered strong revenue growth and double-digit profit and EPS growth. Total revenue growth was 6.5% at constant currency and 1.6% at actual rates as FX translation negatively impacted our revenues by 490 basis points, driven by depreciation of sterling. Like-for-like revenue grew 5.6% at constant rates. Operating profit at constant rates was up 15.4% to GBP 473.9 million, delivering a year-on-year margin improvement of 130 basis points. Diluted earnings per share were 190.8 pence, a growth of 16.8% at constant rates and 11.6% at actual rates. I'll now take you through the high level operating margin performance by division.
Looking more closely at the operating margin bridge, Products delivered a strong operating profit margin of 22.8% and accounted for 90 basis points of group growth. Trade operating margin grew to 9% and contributed 20 basis points to the year-on-year change, while a decline in operating margin in Resources to 5% had a negative -20 basis points year-on-year effect. Divisional mix had a positive 20 basis points contribution, given the strong growth in Products. Finally, FX had a positive 10 basis points impact on the group margin. Our discipline focus on cash management continued during the year. The group delivered adjusted free cash flow of GBP 401.8 million, representing a cash conversion of 132%.
Working capital improved further in 2021, but not as much in absolute terms as 2020, leading to cash generation slightly down year- on- year. In 2021, we invested GBP 96 million in CapEx, up 25% versus prior- year. We finished 2021 with financial net debt of GBP 733 million, which is up year- on- year due to acquisition of SAI, representing a financial net debt to Adjusted EBITDA ratio of 1.1. Now turning to our financial guidance for 2022. We expect net finance costs to be in the range of GBP 35 million to GBP 39 million. We expect our effective tax rate to be between 26.5% to 27%, our minority interest to be between GBP 20 million to GBP 22 million, and CapEx investment to be in the range of GBP 135 million to GBP 145 million.
Our financial net debt guidance before any material change in FX rates or M&A is GBP 640 million to GBP 690 million. I'll now hand back to André.
Thank you, Jonathan, and let's now discuss the performance of our business line, starting with products. As always, and unless stated otherwise, all my comments will be at constant rates. In 2021, our product business delivered a strong performance in like-for-like revenue, operating profit and margin combined with all three measures ahead of 2019. In H2, our performance was excellent as our revenue, profit and margin were respectively up by 14%, 34% and 350 basis points compared to H1. Picking out some of the highlights, both our softline and hardline businesses report double-digit like-for-like revenue growth for the full- year. We benefit from growth in e-commerce and a higher demand for testing of PPEs, home furniture and toys, as well as from the easing of lockdown restrictions.
Our Electrical and Connected World business delivered high single-digit like-for-like revenue growth, benefiting from an increased focus on energy efficiency regulatory standards, more testing of medical devices and 5G equipment. Our Business Assurance, food and chemical and pharma businesses delivered double-digit like-for-like revenue growth in 2021. Business Assurance experienced a rebound in ISO audit, while our food business benefited from a recovery in the global supply chains of our clients. Thanks to a stronger second half, our Building & Construction business delivered stable like-for-like revenue in 2021. Our Transportation Technologies business also bounced back in the second half as OEM investments in new, more efficient and environmentally friendly powertrains picked up in the second half, enabling us to deliver low single-digit negative like-for-like revenue. In 2022, we expect our product division to deliver robust like-for-like revenue growth.
In 2021, our trade business delivered a good performance in like-for-like revenue, operating profit and margin. We saw an acceleration of our like-for-like revenue growth in the second half, enabling us to increase revenue, operating profit and margin by respectively 7%, 57% and 340 BPS versus the first half. Caleb Brett recovered as global mobility picked up with improved momentum in the second half, resulting in low single-digit like-for-like revenue for the year. Our Government and Trade Services business showed a slowdown in the second half a little bit due to supply chain disruptions in some of our markets, resulting in low single-digit like-for-like revenue growth for the year. Benefiting from growing demand for food inspections, the AgriWorld business delivered double-digit like-for-like revenue growth in both the first and the second half of the year.
In 2022, we expect our trade divisions to deliver robust like-for-like revenue growth. For the full- year, our resource divisions delivered a solid like-for-like revenue performance with a margin performance below 2020. In the second half, we saw like-for-like revenue growth acceleration in each of our three businesses. Compared to H1 revenue was up 7%, operating profit was up 11%, and margin was up 10 basis points. Our CapEx inspection services business delivered stable like-for-like revenue growth in H2 as our oil and gas clients started ramping up their investments. OpEx maintenance services picked up in the second half and delivered mid-single-digit like-for-like revenue growth. Increased demand for testing and inspection activities saw mineral business deliver double-digit like-for-like revenue growth in the second half. In 2022, we expect our resource business to deliver good like-for-like revenue growth.
Let's now discuss the growth outlook for the group moving forward. COVID-19 has been much more than a tragedy for the world. In our view, COVID-19 will be remembered as the greatest dislocation of the global supply chain since the seventies, creating significant challenges across the world. Our clients have realized that they will need to increase their investments in quality assurance to operate with high quality, safety and sustainability standards. Indeed, COVID-19 has made the case for Total Quality Assurance stronger. At Intertek, we are supporting our 400,000 customers every day as they try to synchronize their sourcing, production and logistics activities. The supply chain disruptions within the ecosystem of our clients are highly complex and although everybody is working hard, it will take time before the global supply chain is back to normal.
There is a major learning for our clients from this significant global supply chain dislocation. They've been operating with substantial intrinsic risks in their supply chains without the right data, process and independent assurance. That's why 80% of companies will increase their investment in quality assurance to strengthen their operations. Based on the extensive discussions we've been having with our clients, these investments will be in three areas: supply chain resilience, innovation, and sustainability. COVID-19 is indeed proving a catalyst for many corporations to improve the resilience of their supply chains. We expect corrective actions, and these will include better data on what's happening in all parts of the supply chain, tighter risk management with razor-sharp business continuity planning, a more diversified portfolio of tier one, tier two, tier three suppliers, a more diversified portfolio of factories, investment in processes, technology training, and independent assurance.
We're also seeing our clients realize that in addition to their supply chain challenges, they need to invest more in product and service innovation to meet the changing needs of their consumers. As you would expect, during a major global crisis like COVID-19, consumers' expectations are changing given the desire to live in a much better world. Corporations need to step up their game in quality, safety, sustainability, convenience, and value for money to enhance their products and services. The third major area of investment inside corporations is, of course, sustainability. The sprint to Net Zero emissions is real, and corporations are having to reinvent the way they reduce their carbon footprint across the entirety of their operations and the way they communicate the progress they make on Net Zero.
The supply chain disruptions experienced by corporations across multiple industries has made the need for comprehensive risk-based quality, safety, and sustainability assurance more critical than ever. All stakeholders in society expect governments and corporations to build back a better world with a sharper focus on end-to-end quality assurance. The quality assurance market will grow faster post-COVID, capitalizing on the unchanged, strong structural growth drivers pre-COVID, and benefiting from companies' increased investments in resilient supply, innovation, and sustainability. The like-for-like revenue growth outlook for quality assurance moving forward is GDP plus in real terms. We are well-positioned to benefit from the increased investments of our clients in quality assurance. We are the global leader in risk-based quality assurance, giving the depth and breadth of our unique ATIC solutions, underpinned by our continuous investment in M&A and innovation to address the emerging needs of our clients. I've already mentioned M&A.
Let's talk about innovation. Investment in innovations to meet the emerging needs of our clients in quality assurance are essential to deliver a superior ATIC customer service. Let me remind you our approach in innovation. We pursue a three-tiered approach to innovation, building on the strength of existing services, which we call innovation from the core, developing new products and services in adjacent, fast-growing and high-margin markets, and developing breakthrough services, creating new markets. In the last few years, we've shared with you the strategic investment we've made through acquisitions and innovation to strengthen our portfolio of ATIC solutions. These investments in high-growth and high-margin segments were made within a disciplined capital allocation framework. We are scaling up these successfully as evidenced by our excellent organic ROIC of 24.4%. We constantly look at opportunities to invest in new growth opportunities in high-margin sectors.
Our team are working on exciting new ideas to continue to strengthen our ATIC value proposition. Let's now discuss the outlook for 2022. Given our well-diversified revenue streams across industries and geographies and the strong progress we've made in H2 2021, we enter 2022 with confidence. Notwithstanding the supply chain challenges that our clients are facing in some markets, we expect the group will deliver robust like-for-like revenue growth at constant currency, with margin progression year- on- year and a strong free cash flow performance. We'll continue to invest in growth, and we expect our full-year CapEx investments to be circa GBP 135 million to GBP 145 million. We expect our financial net debt to be in the range of GBP 640 million to GBP 690 million. A quick update on currencies for your model.
The average sterling rate since the beginning of the year applied to the full- year results of 2021 will be broadly neutral at the revenue and earnings level. I would like to finish our call with a few remarks on how important sustainability is for all of us at Intertek. Sustainability is, of course, the movement of our time. We are a purpose-led company, living our strong values every day. The global pandemic has demonstrated what we do at Intertek is mission-critical to society. Our role of bringing quality, safety, and sustainability to life has never been more important. All of us at Intertek are passionate about making the world a better and a safer place. I can proudly say that Intertek is an amazing force for good. Sustainability is about delivering sustainable value for all stakeholders, starting with our customers.
Every day at Intertek, we focus on our vision of being the world's most trusted partner for quality assurance. That's why we are a very customer-centric organization. We never stop reinventing ourselves to deliver superior ATIC service to our clients. This is how we help our clients build strong businesses, capitalizing on Intertek science-based customer excellence. What our clients are looking for today is a systematic, independent, end-to-end assurance on all aspects of their sustainability journey. Our answer is Intertek's unique Total Sustainability Assurance, a holistic program empowering our customers to achieve sustainability excellence across all aspects of their businesses and communicate results with confidence. Intertek Total Sustainability Assurance is comprised of 3 parts: our Intertek Operational Sustainability Solutions, Intertek ESG Assurance, and Intertek Corporate Sustainability Certification. Intertek Total Sustainability Assurance is a global program leveraging our footprint in over 100 countries and covering all industry.
We build a team of sustainability experts in every major region who can help their clients with both a global and a local perspective. Thought leadership and innovation is what set us apart. Internally, we are focused on sustainability excellence in every single operation. We believe that doing business the right way with a systemic approach is the only way to deliver our corporate goals. To do that, we follow precise sustainability processes in 10 areas. We are targeting Net Zero emissions by 2050, and starting in 2022, we have included a carbon emission reduction target in our short-term incentive for all employees, in addition to revenue, profit, and ROIC. Sustainability is, of course, much more than achieving Net Zero. We pursue beyond Net Zero targets in the areas of customer satisfaction, diversity and inclusion, health and safety, compliance, employee turnover, and engagement.
Moving forward, we'll continue to deliver sustainable growth and value for all stakeholders. Our USP at Intertek is our science-based customer excellence in quality, safety, and sustainability, giving our 400,000+ clients the ATIC advantage to strengthen their businesses. We operate a high margin, capital light, carbon light, and cash-generative earnings model. Intertek's approach to value creation is based on the compounding effect year- after- year of margin equity revenue growth, strong cash generation, and disciplined investment in growth. In summary, we have a clear purpose of making the world a little better, and our leading ATIC solutions are what society needs to build back ever better. The growth in our end market is accelerating, given that our clients have realized during COVID-19 that too many risks in their supply chain were not properly mitigated.
Given our strong market leadership positions and our science-based customer excellence, we are well positioned to seize the exciting growth opportunities ahead. We are a high-quality global growth business with a track record of continuous growth in revenue, margin, cash, and dividends, delivering an excellent ROIC. Moving forward, we'll continue to deliver sustainable growth and value for all stakeholders.