Hi Graham,The label looks the same as the ones on my seats,same shape size and black background.A lot of aircraft seats were made by furniture manufacturers and the aircraft type stamped on the labels.My seats are stamped different numbers with only the SB for shorts bros and the number to ID which seat position in which sort of aircraft.My flight engineers seat is stamped SB20 and for years I thought it was the aircraft type.I think the clue may be in the RGS stamped on the label.
Looking at the construction,I would say it was once `slung` with material similar to a passenger or observers seat.

The label on the seat looks very similar to a british `rumbolds` label..

That looks really nice John,Is that control column and surround in its final fixed position now?