if you remeber the class 465 that stayed in Network SouthEast livery from privitisation through to connex southeastern then southeastern trains (holdings)then govias SouthEastern where it was sent to get southeasterns charcoal livery some enthsusiasts even called the train 'the great escape' i dont know what number it was but ill find it out and tell you's.
southeastern-465 (NSERS member)
so it lasted nearly 11 years!