My Land Rover has an identical shape switch although black. It switches off the "P" for panel lights when not required, after turning on lights. This was quite common in early cars with dynamo charging as every milliamp counted
I had a couple of old MOD Land Rovers - they also had the 'convoy' light - it would turn all the lights off, bar a small low powered bulb above the rear diff (which was painted white) for night time stealth operations.....
"Y mae dafad ddu ym mhob praidd" 1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10
