Hi,
You have to have amber direction indicator lamps, front and rear, in the UK to get through an MOT test in your car. Here is a quote from the official MOT manual...
"Direction indicators must be amber.
Vehicles first used before 1 September 1965 may have white front indicators and red rear indicators, if the direction indicators are combined with stop lamps or combined with front or rear position lamps.
Vehicles first used before 1 April 1986 don’t need to have hazard warning devices."
The whole manual can be found here...
https://www.mot-testing.service.gov.uk/documents/manuals/class3457/Section-4-Lamps-reflectors-and-electrical-equipment.html#section_4.1
But, rather than wade through the whole thing get over to DDK were many others have been through the process of getting early 911 imported from the US through the UK tests and registration...
DDK-Online
Mark