Hello, I'm Andy Walters, founder of Quartix Technologies . I returned to the company at the end of 2023 as Executive Chairman. This presentation covers our interim results for 2025, and it's available to download together with our interim report on our investor site. Our customers are typically SME companies with mobile workers who travel to customer sites for their work. Through tracking their vans, we provide them with business and operational information on a subscription basis using web and mobile-based applications. This has always been the basis of our business. The most significant financial benefit to them of using our service is that of increased business capacity. Our base has grown strongly since 2001, and today we have almost 320,000 vehicles under subscription. We started out in the UK, but have added five other target markets since, and our systems are entirely based on in-house owned and developed IP.
This chart shows the equivalent growth in our customer base, also split by market. Our customers are typically in sectors such as construction and building, service and maintenance, land and grounds work, and the public sector. In fact, 60% of our customers are now outside the U.K., and these markets are growing at a rapid rate for us. Since my return, we've put our entire focus on our core telematics subscription business, registering record levels of progress on key measures, one of them being the rate of customer acquisition. These three green lines show progress in this measure between 2020 and 2022. There was a loss of momentum in 2022, resulting in weak performance in 2023, which we successfully turned around by the middle of 2024, establishing a period of record customer acquisition, which has continued into 2025. We added almost 4,000 new customers in the first six months.
Another key measure is the value of our subscription base, annualized recurring revenue (ARR). It's the key indicator of our future revenues and profit. We increased ARR by a record GBP 3.5 million in 2024. That was 68% ahead of the growth achieved in 2023. In just the first six months of this year, we added another GBP 2.7 million, taking us to GBP 35 million. Growth in ARR needs to be achieved cost-effectively, and we've made great improvements here also by significantly reducing and redirecting overhead spend. Another important indicator of the health of our business is net revenue retention. This measures how much we retain in value terms of our customer base each year. At the end of June, we'd retained 97.3% of our ARR from 12 months earlier. This has improved by more than four percentage points since the start of 2024.
ARR growth in the 12 months to the end of June was GBP 4.1 million. To put the improvement in context, this slide shows the company's progress from 2020 to 2022 in the three green lines, detailing cumulative growth in ARR through each of those years. Performance slipped in 2022, resulting in weak performance in 2023. This was turned around, and in 2024, you can see in these lines the improvement that was made. The chart splits that ARR improvement by market. The top left shows ARR by country, and the bottom right shows the contribution made to growth in millions of pounds by each country. This latter chart gives a better indication of the potential of each market. Growth in the UK almost doubled. France made the strongest contribution.
The USA was turned around from a deficit to a gain of GBP 0.3 million, and Italy, Spain, and Germany, where we've been present for just six years, made excellent contributions with particularly notable progress in Italy and Spain. Revenue in the first half increased by 10% to GBP 17.6 million compared to last year. Operating profit increased by 31% to GBP 3.5 million, and EBITDA was GBP 3.7 million, an increase of 30% over 2024. The net result was earnings per share of GBP 0.0552 versus GBP 0.0449 last year. We're paying an interim dividend of GBP 0.025 per share. Cash generated from operations was strong, up by 72% to GBP 3.2 million, or 89% of operating profit, and free cash flow was GBP 2.5 million, more than double the result for 2024. This was achieved despite cash costs of approximately GBP 0.5 million for the 4G upgrade program in France.
We made good progress in product development, particularly in hardware. Development of our latest telematics system, the TCSV 17, was initiated and released to production in 12 months. The development marked the most significant revision of both hardware and firmware for at least a decade. The design objectives were focused principally on cost reduction, but some significant advances have also been made in performance. The cost saving achieved is approximately GBP 8 per unit, and that new model will account for around 7,000 units per month of usage from now on. Initial versions of revised web-based and mobile tracking applications were developed and released during 2024. The mobile app was completed in January this year, and development and rollout of the new web-based application will be accelerated in 2025. All of our investment in research and development is fully expensed.
Everybody at Quartix has worked hard at refocusing the business on its core telematics subscription service. We've achieved strong revenue and profit growth while reducing overheads and increasing investment in sales and marketing. We've adjusted pricing to help compensate for the inflationary pressures felt in 2022 and 2023, and we'll continue to do so. The net result has been the achievement of record growth in ARR and a 31% increase in operating profit. Free cash flow has more than doubled. The board believes that there's significant scope for growth in its existing six markets, and this will remain the focus for 2026. The group has shown great progress in the first half of 2025, and the outlook for the remainder of the year is very encouraging. We look forward to the future with confidence. Thank you very much for listening.