Not_a_boffin mentioned weight growth.
The Vulcan put on over 5 tons during its life with the first major weight increasing being over 8000 sq ft of polyurethane paint.
I don't know about weight growth on others but I do know there was a problem between the Mk 1 and Mk 2 Nimrods which meant the latter had to manoeuvre on the ground at low speeds. On the Mk 3 it required the deck to be reskinned and carpetted to save weight and for the Mk 4 to be re-winged and have a stringer undercarriage.
You can argue that warships are bigger than aircraft but then you have more space within which to work and more people can work at the same time.