pba may have misread but a Canberra still fits the bill. WJ874 was a T.4 taken on RAF charge in December 1954. Left RAF service November 2005 - that's 49 years!
And, this airframe is still extant - Air Atlantique now own it. Affectionately known as "The Blue One", it was painted to represent the prototype VN799.
Edited to note that vecvec has changed the gist of his post so my first sentence now means nothing!