cheers for this info -I will get hold of a volt meter and test each circuit -hope its the earth at the socket end! -where will it connect up if its the engine end?

anyone got any ideas why my 1972 series 3 SWB safari has no trailer lights or left hand indicator? Right indicator and brakes are fine, light board is fully working -I have checked and reconnected the wiring in the socket but still nothing? Hoping there might be something obvious rather than a...