How vital was George Martin – who died yesterday at the age of 90 – to the extraordinary whirlwind of innovation and creativity that represents the recording career of The Beatles over eight short years?

Following the band's poisonous split at the start of the 1970s, John Lennon told Paul McCartney that the producer's importance had been overstated: "When people ask me questions about, 'what did George Martin really do for you'? I have only one answer; 'what does he do now'? I noticed you had no answer for that! It's not a putdown, it's the truth."

Within a few months, though, he had retracted. “George Martin made us what we were in the studio. He helped us develop a language to talk to other musicians.”

Martin himself wrote in 1979 that “without my instruments and scoring, very many of the records would not have sounded as they do. Whether they would have been any better, I cannot say. They might have been. That is not modesty on my part; it is an attempt to give a factual picture of the relationship.”

It doesn’t diminish the achievement of the four Beatles – Lennon and McCartney in particular – to say things would almost certainly have worked out very differently without Martin’s input. It’s genuinely hard to see that the group would or could have followed the same trajectory without him. And while instruments and scoring were at the heart of their collaborations, Martin’s contribution ran both broader and deeper.

Rejected

First, he saw something in the group when nobody else in the industry did. The Beatles had already been rejected by nearly every British record label by the time Brian Epstein, the group’s manager, arrived at Martin’s Parlophone Records in early 1962. Martin turned them down, too, at first, but was prevailed upon to reluctantly grant a recording session with his assistant, Ron Richards. When Richards sent word the session was going well, Martin took over and was impressed by the attitude and personalities as much as by their music.

At the time, Parlophone was best known for comedy and novelty records, but Martin was seeking to expand into rock 'n' roll. Having recognised The Beatles' potential, he was very clear about what was required for success, making sure the group replaced their drummer, Pete Best, with Ringo Starr. He also encouraged them to be less derivative, to inject greater energy and personality into their songs and to work harder on structure and harmonies. The result was a fresh, young, distinctively British sound that struck a nerve with a new generation, first in the UK and then across the Atlantic.

With their Liverpudlian accents and moptop haircuts, The Beatles played up the notion of Martin as an upper-crust toff trying to put manners on them in the studio. In fact, he was a scholarship boy, the son of a carpenter and a cleaner, and from a poorer background than most of the group.

As Beatlemania swept the world, he worked on broadening the group's sound. Martin's own musical hinterland (he had supervised recordings by the London Baroque Ensemble and conductor Malcolm Sargent, as well as jazz musicians John Dankworth and Stan Getz) led him to encourage the Beatles to break away from bare bones rock and pop. On albums such as Help! and Rubber Soul, he encouraged a fuller, orchestral sweep that would influence future musicians.

"I brought the song Yesterday to a recording session and the guys in the band suggested that I sing it solo and accompany myself on guitar," McCartney recalled in his statement following Martin's death. "After I had done this George Martin said to me, 'Paul, I have an idea of putting a string quartet on the record'. I said, 'oh no, George, we are a rock 'n' roll band and I don't think it's a good idea'. With the gentle bedside manner of a great producer he said to me, 'let us try it and if it doesn't work we won't use it and we'll go with your solo version'. I agreed to this and went round to his house the next day to work on the arrangement.

So thrilling

“He took my chords that I showed him and spread the notes out across the piano, putting the cello in the low octave and the first violin in a high octave and gave me my first lesson in how strings were voiced for a quartet. When we recorded the string quartet at Abbey Road, it was so thrilling to know his idea was so correct that I went round telling people about it for weeks.

“His idea obviously worked because the song subsequently became one of the most recorded songs ever, with versions by Frank Sinatra, Elvis Presley, Ray Charles, Marvin Gaye and thousands more.”

Martin was happy to broaden further the definition of what a pop group could sound like through importing ideas from the avant garde and from cutting-edge recording technologies of the day, including the earliest forms of electronic music. It helped that, in the late 1950s and early 1960s, he had worked with Peter Sellers, Spike Milligan, the Goons and other absurdist comedians to produce a string of often surreal novelty records where rules were made to be broken.

Producing Sgt Pepper's Lonely Hearts Club Band was, he said, "a postgraduate exercise after Sellers". But that psychedelic flagship was also the culmination of two years of increasingly sophisticated and experimental techniques, stretching the capabilities of existing tape technologies to their limit and beyond on tracks such as Tomorrow Never Knows from Revolver, and on Strawberry Fields Forever, the standalone single (a double A-side with Penny Lane between Revolver and Sgt Pepper.

It was a remarkable moment in the history of popular music; across the Atlantic, Brian Wilson was also breaking moulds with his Beach Boys album, Pet Sounds. A musical revolution was taking place, led by some of the biggest pop stars – and increasingly by producers as well.

As the hair got longer, the drugs got stronger and the band started to disintegrate, Martin remained an anchoring presence in the studio in his shirt and tie, through the White Album, Abbey Road and even the fractured and divisive swansong Let It Be (which was reworked controversially by another Sixties studio legend, Phil Spector).

For a time, Martin bridled at the fact his other work was so overshadowed by his eight years with The Beatles (among other things, he virtually invented Merseybeat, producing Gerry and the Pacemakers, Cilla Black and Billy J Kramer; and was also responsible for two James Bond songs, You Only Live Twice and Live and Let Die). But he became comfortable with that legacy, and returned to it in the 1990s with Anthology, a project including documentary films and previously unavailable Beatles material.

“If anyone earned the title of the fifth Beatle it was George,” McCartney said definitively yesterday. “From the day that he gave The Beatles our first recording contract, to the last time I saw him, he was the most generous, intelligent and musical person I’ve ever had the pleasure to know.”