Finally, the class 97/3 (as mentioned in one of your early posts) are four locomotives refurbished and reclassified from class 37s. They retain their class 37 body shell, so they look identical except that they are bright yellow!
https://en.wikipedia.org/wiki/Britis...%E2%80%9397304
The four locos (Nos.97301-97304) are operated by Network Rail, mainly on test trains.
Tony