Would you class them as yellow or Amber/Orange?
If Amber/Orange then illegal....
In the flesh they are more yellow than orange but we shall see - I have driven past a couple of Police cars without incident... (famous last words!)
Unlikely police will bother unless it’s part of a more serious stoppage.
The MOT inspector will have the final say! MOT manual states white or yellow.
My wife's car once failed on rear indicators because the inspector decided that the OEM orange bulbs were not quite orange enough!