It's not just all the great songs Paul McCartney has written (more than any other British composer) that make him, in my opinion, the greatest living Englishman. As one of The Beatles, Paul had a massive cultural influence in the 1960s, whether it be music, fashion, or encouraging people to appreciate art through The Beatles album covers of Klaus Voormann (Revolver), Peter Blake and Jann Haworth (Sgt. Pepper's Lonely Hearts Club Band).
In addition, Paul's support of animal rights has encouraged people to be more compassionate. It seems then that love being a common theme in the music of The Beatles is no coincidence.
Here's a piece I wrote about Paul McCartney a few years ago, and this page also features an appreciation of Paul McCartney by Andy Savage written in 1988.