Watched a re-run (More4, Sunday PM) of Howard Goodall's 20th Centuary Greats about The Beatles. He was very complementary about their writing (use of modes, modulation etc) and how they saved modern classical music (i.e. it was okay for modern classical composers to write tunes again:-)). He stated that one reason for their musical adventurousness was that during their time in Hamburg they had to play all sorts of music (show tunes, rock and roll etc etc.) the role of George Martin was scarcely mentioned. This lead me to thinking up this question.

How much of the success and musical innovation was down to (or at least co-authored) George Martin?