The Ilford Witness, along with the Reid cameras, were quality British-made interchangeable lens 35mm rangefinders produced for a few years in the late 1940s and early '50s while the German photo industry was rebuilding itself after the War. (cf. the MPP Microflex and Microcord TLRs.) Unfortunately they were not made in large numbers or for very long.
Continuing with the courtroom theme, Ilford also had a simpler, non-rangefinder model called the Advocate.
Unlike the other cameras you mention the Witness was an entirely new camera,and with production of less then 350 you can't say successful, they sell for a lot of money these days.
The other British cameras mentioned were basically of German camera design with British engineers having access the factories as part of war reparations. So the Reid is a screw mount Leica clone, the Microcord a Rolleicord clone, there was also the MPP MicroTechnical which is a Linhof Technika clone, there were others as well based on the Reflex Korelle.
My father, a mechanical engineer, was sent to Germany after the IEME tank regiment he commanded became part of the new Indian army at the end of WWII. REME was the British Royal Electrical and Mechanical Engineers corps, and IEME was the equivalent but with Indian (Sikh) troops) He only told us a few days before his death that he'd spent time in Germany after the war, I know he was at a major engineering conference in the UK shortly before the war in Europe ended as I've found the list of people who attended, and he's listed as Lt Colonel J M Grant, IEME, and ironical one of the few military engineers present. So far I've no idea what my father actually did in Germany, his sister was at the Nuremberg trials working for a high ranking British Military commander.
Of course it wasn't just the British gathering information, the US and Russians were too but they often took machinery and personnel as well
Ian
It was RAF personnel who went into the Photographic companies and work was published in classified FIAT reports.