Does anyone know the live wire colour for the rear light (the light that turns on with the first click of your light switch/dial) been told mine is flashing but don't know which wire colour it is to check the connection?

Is the bulb seated right or on the way out? I wouldn't (usually) expect the wiring to be at fault.

It was one wire that was faulty he told me it needed sorting when I bought it

Year/Engine/Edition?

Left or right tail light?

Standard VAG colours are :-

Left - grey/black

Right - grey/red