Peerless folklore says that these switches came from a Landrover, but (as far as I know) early Landrovers have a changeover fuel Tap fitting, which isn't electrical.
Early Jags do have a similar fitting, see: www.holden.co.uk Code=31429 Expensive!
Cheaper multi pole, multi way rotary switches are common electronic items, but will not take fuel pump current for long.
On my Warwick, I have a 6 gallon single tank, and have used the dash hole for Hazard Flashers. (England is only a small country and you don't need 16 gallons to get to the next petrol station.)