2 inch Hitachi HS124E image orthicon tubes

[ppppenguin]

An amazing find. I'd never heard of 2" IO. Like the OP I thought they only came in 3" and 4.5" diameters.

Originally Posted by BrianSummers

In the early days the BBC would not buy tubes but had them on "rental" and returned them after a certain number of hours of use.

This was certainly true for the pre-war Emitrons. The interesting question is whether this rental arrangment was at the insistance of the BBC or the tube makers.