The Thorn 2000 chassis dates from 1967/68. Not sure of the exact date but I don't think it was available for the very start of the UK's colour service. The UK colour service started on BBC2 only in 1967. BBC1 and ITV were still on 405 lines until 1969. The event in Birmingham was to celebrate colour on all the UK channels.
All subsequent colour TVs from Thorn (HMV, Ultra, Ferguson brands) were also fully solid state. The 2000 was dual standard: 625 colour and 405 monochrome. This gave a lot of extra complications, including 3 solenoid operated system switches. The 3000 chassis was 625 colour only and was produced in large numbers, both for sale and for rental. It had an early switchmode power supply. Contrast with the 2000 and its linear regulators and separate EHT that made it more like a professional monitor in some respects.
In the UK (and the rest of Europe) we benefitted from over a decade of American experience with colour. Our first CRTs were rectangular with rimband protection. Our first cameras were Plumbicon.
With the benefit of hindsight it might well have been better to choose a 625 version of NTSC in Europe. At the time it was thought that NTSC was too prone to various colour distortions so we ended up with PAL and SECAM. Further down the line this gave a lot of problems doing accurate recovery of video archives - it's a lot harder to do good comb filtering of PAL than NTSC. SECAM is worse still. But with transistors and ICs to give more stable circuitry, NTSC became capable of much improved results.
Hindsight is a wonderful thing. I think of the grief that changing 60Hz to 59.94Hz has given to the world of TV production. It seemed like the easiest way to make NTSC work well without needing to retune the sound IF on millions of TVs. Then somebody invented timecode and we've had to cope the problem ever since.
PS: The info on the Radiomuseum site is wrong:
https://www.radiomuseum.org/r/hmv_co...r_brc2000.html The 2000 series was made by Thorn at Enfield, not EMI at Hayes. For some years the Thorn group had the rights to the HMV brand name for TVs and other electronics while EMI owned the HMV brand for records etc. In 1979 Thorn merged with EMI. At least it was called a merger; EMI were in big trouble and Thorn took them over. The 19" 2701 model was less common than the 25" 2700.