[Argus25]

That CRT is certainly unique. It would probably be the only CRT of that era, for television use, that was electrostatically deflected. I guess Sinclair would have had to have made that themselves, I cannot think of any other commercial small screen sets of this vintage that were not electromagnetic deflection. Electrostatic deflection is quite good and energy efficient for small sized screens, only a problem for screens a lot larger than 5". All the small 1" sized viewfinder CRT's that turned up in video cameras in the 80's, were mag deflected.