Proctor Part Queries.

I’m hoping that there may be some Proctor buffs on this forum to assist with a couple of questions. I’m seeking to establish commonality of parts between the different Marks of Proctor and earlier Percival aircraft.

Fuel Tank Selector.

1. Fuel Tank Selector;- Was the same unit utilised on all Marks of this machine?
2. Was it a Percival-specific item, or was it used on other a/c?
3. Who made it?
NB;The surviving Vegas and Gulls seem to have used a different unit, in a different position. Is there any evidence of the Proctor unit being used earlier..?

U/C

4. U/C- Did all Marks use the same U/C leg with the separate, external damper.
5. Was it a Percival-specific item?
6. Who made it?

Any help gratefully received…!