He hadn't seen them live, called their demo tape "unpromising" and thought their original songs weren't very good. So why did he sign them?
After asking the band if there was anything they didn't like, and George Harrison -- then only 18 -- told him, "Well, there's your tie, for a start."
Paul McCartney wanted to bridge the gap between his and Lennon's sections of 'A Day in the Life' with a full orchestra making a hell of a racket.
Martin, having a background in classical music, knew the musicians wouldn't be able to properly improvise the atonal crescendo McCartney had in mind -- so he wrote a score for it.
"What I did there was to write... the lowest possible note for each of the instruments in the orchestra," Martin explained.
"At the end of the 24 bars, I wrote the highest note... near a chord of E major. Then I put a squiggly line right through the 24 bars, with reference points to tell them roughly what note they should have reached during each bar."
By late 1966, Lennon's mind had been opened (or addled, it's up to you) by LSD, and his compositions were becoming increasingly strange -- few more so than 'Strawberry Fields Forever'.
Happy with the first half of one take and the second half of another, Lennon tasked Martin with finding a way to piece them together -- despite the first half being recorded at a different speed and tempo to the first.
Saying Martin fired Pete Best from the group might be overstating it a little, but it was his call not to use the quiff-wearing drummer on their first proper studio recordings.
"It was pretty tough for him and I felt guilty because I felt maybe, I was the catalyst that had changed his life -- so I'm sorry about that, Pete."
"At that stage 'Please Please Me' was a very dreary song," Martin once explained. "It was like a Roy Orbison number, very slow, bluesy vocals. It was obvious to me that it badly needed pepping up."
Eighteen takes later, Martin told the band they'd just recorded their first number one hit -- and he was right.