Pachelbel's Canon in D has contributed to this song and lots of others. Al Stewart used to claim (and probably still does) that McTell nicked the tune of "Streets of London" from Stewart's song "Oh Samuel, How you've Changed".

The chord sequences are virtually identical, and sometimes, for a bit of fun, I segue "Oh Samuel..", "Streets..." and Steve Goodman's "City of New Orleans", using more or less the same accompaniment for each, and end up by playing the first few bars of the Pachelbel Canon on guitar.

Pretentious, moi!?!

Alan