A tea-break in the hit factory for George Martin and the Beatles, as John Morrish rewinds the tape.

One of the earliest photographs of George Martin with the Beatles shows the elegant producer with his group in EMI's Abbey Road studio canteen. The four Beatles look out at the world with the famous boyish charm that was to ease their path to massive international success. And in the corner, head propped up on one elbow, is George Martin. He looks like an anxious young probation officer taking his charges on an outing. He is wearing an expression that says precisely this: "What the hell have I let myself in for?"

Never could he have imagined the successes that were to come. Indeed, when the shot was taken he had no great confidence in the group's abilities.

"I didn't think they could write music. I didn't sign them because they were great composers because they weren't; they were rotten composers. If I remember correctly there were only one or maybe two of their own songs in that first audition and they weren't very good — 'PS I Love You' and 'Love Me Do'. They hadn't shown any evidence of what was to come in the way of songwriting," he told Brian Southall, Abbey Road's official historian.

What Martin liked was their obvious wit, and their potential as a live act. With a few reasonable singles to back them up they could be very high earners on the live circuit. But the band and its young manager Brian Epstein had higher ambitions. Epstein would tell anyone who would listen that his boys were going to be bigger than Elvis, which meant selling massive amounts of records all over the world. It was an old boast that made people laugh behind his back — the strange thing is, he was right.

It is no wonder that George Martin didn't rate the foursome very highly: a nursery-rhyme dirge like "Love Me Do" was a long way from anything that the cultured ex-BBC man knew as music. It must have sounded strange, too, echoing around the lengthy corridors of EMI's Abbey Road studios, the recording factory for a company that considered itself a British institution, almost a Ministry of Music. EMI had the Shadows and they had Helen Shapiro, both of whom did very nicely for them, at least in Britain. What's more, both of them were shaping up to become good all-round entertainers, the perennial goal of the entertainment industry.

George Martin had an unusual background for a man who was to become the most important British record producer of the 1960s. In the first place, he was a highly-trained musician, having spent three years at the Guildhall School of Music and then a period as a freelance orchestral oboe player. Then he had a spell with the BBC: some say in a clerical position, or perhaps headed for a post as a news reader.

He arrived at Abbey Road in 1950, abandoning an ambition to be a concert pianist, and became assistant to the head of Parlophone Records, EMI's third-string label. Parlophone struggled through the 1950s because it was not allowed to import the sort of American material that gave HMV and Columbia their major income.

So George Martin was under constant pressure to find new British artists and songs. And then there was the comedy. Martin had inherited several comedy acts, but he took things to new heights, even putting comedy singles from Peter Sellers, Bernard Cribbens and others into the charts.

He wasn't, in fact, a producer then. He was an "Artistes & Recording Manager". (A&R later came to mean "Artistes & Repertoire"). Sessions were effectively run by the studio's veteran engineers, many of whom preferred to record on wax rather than tape, and objected to "artificial" echo.

Martin's artists produced light orchestral music, dance music, even some chamber music, and for the most part his function was limited to watching from the control room. "I think my producing career really started with those comedy records, because I was getting very involved on the floor instead of just being in the control room saying 'Yes, that's nice' or 'You're singing a bit flat'. It became a matter of going through material and saying 'Let's not do this. If we put a bit of music behind this, or have the sound of a bandsaw coming in from the left, it'll make it much better.' It was creating before we got into the studio at that stage, and really that's what a producer is up to — he's sort of masterminding the concept of what it's going to sound like before it actually happens, and the comedy records were tremendous training for me in that," he told John Tobier and Stuart Grundy.

And the sessions with people like Sellers, Spike Milligan and Peter Ustinov had technical benefits too. "People like these played a big part in teaching others at Abbey Road how to use tape. It was still in its infancy and a lot of people at the studio regarded tape with a great deal of suspicion but we gradually learnt all about it. Working with the likes of Sellers and Milligan was very useful, because as it wasn't music, you could experiment.

"We made things out of tape loops, slowed things down and banged on piano lids... these were the synthesisers of the day," he said.

The comedy records were important, too, because they provided some common ground when the Beatles arrived. They were about all the avuncular producer and his Liverpudlian charges did have in common, at the beginning. But the first audition was important for both sides. Brian Epstein's management had, at that stage, taken his boys precisely nowhere. Parlophone needed its own answer to the Shadows, then the only significant name in British pop.

But George Martin was horrified by what he heard. The sound they made was terrible: he immediately set an engineer to repairing their amplifiers. In the end Paul played his bass through a Quad Acoustical studio amp and a Tannoy monitor speaker. And then Martin put them through their paces, together and apart, instrumentally and vocally. He told Epstein that the drummer Pete Best had to go.

Epstein obliged, and when they came back they had a new drummer and had rearranged their audition song "Love Me Do", so that it started with an attractive harmonica riff.

Martin insisted on using the session drummer he had booked, and engineer Norman Smith recalls the session for the first single taking the unheard-of time of about a fortnight. But "Love Me Do" was released to become a modest hit, assisted no doubt by Brian Epstein's precautionary purchase of 10,000 copies for his Liverpool record shop.

For the follow-up, Martin went out to the "professional" songwriting market and offered them "How Do You Do It", a jaunty little number later recorded under his supervision by Gerry and the Pacemakers. The Beatles hated it, pushing instead their own "Please Please Me". But Martin lectured them, "When you can write material as good as this, I'll record it. But right now you're going to record this."

So they recorded it, giving it a dreary lacklustre performance that effectively damned it. The song is still in EMI's vaults. So it was back to "Please Please Me", written as a slow Roy Orbison-style number. At Martin's suggestion, they added a harmonica introduction, sped the song up, and put an extra chorus at the end. With Ringo behind them, the group finished the song in the first take. "George Martin's contribution to our songs was quite a big one," says McCartney.

When they came to do an album, they put down 10 tracks in 13 hours, an achievement now considered near-miraculous but fairly normal in those far-off monophonic days.

Effectively, the group gave a concert in the studio, while George Martin put their instruments on one channel and their voices on the other. Then it was just a question of balancing one track against the other for mono issue.

The group, plus George Martin, became an inseparable studio quintet from then on. But Martin still had lots of other work to do. Indeed in 1963, his records held the number one spot for 32 weeks out of 52.

One of his charges was Gerry Marsden and his Pacemakers. In 1963, Martin put his formidable technical skills as an arranger to work and provided him with a shimmering string backing for "You'll Never Walk Alone".

When Paul McCartney came into the sessions for the "Help" soundtrack with a gentle tune with no lyrics, called "Scrambled Eggs", Martin recorded it with no drums and asked Paul for advice as to what to do next. He suggested strings "but Paul said, 'Oh, I don't think I want Mantovani and Norrie Paramor, thank you very much.' I think he'd probably heard what I'd done to Gerry & The Pacemakers," said Martin.

Instead, Martin suggested a small string group, perhaps a string quartet, and Paul, now living with the family of Jane Asher and rapidly immersing himself in all things cultural, readily agreed. It was an obvious turning-point, as Martin declared in his autobiography "All You Need is Ears": "That was when, in retrospect, I started to leave my hallmark on the music, when a style started to emerge which was partly of my making. It was on 'Yesterday' that I started to score their music. It was on 'Yesterday' that we started to use instruments or musicians other than the Beatles or myself (I had often played piano where it was necessary)."

Martin's arrangement was undoubtedly at least half the secret of the song's phenomenal success. It is a long way from what the average commercial arranger might have attempted, a genuinely strong piece of string writing in which the rasp of gut is clearly heard, a rarity in pop arrangements. The arrangement compensates for the rather conventional sentiments of the lyric.

Meanwhile, on the technical front, EMI's innovative engineering department had provided Abbey Road with a set of 4-track recorders.

They arrived in November 1963, but such was the pace of the Beatles' recording and film commitments, it was not until 1965's "Rubber Soul" album that the group and their producer got a real chance to try them out on new material.

The album marks the beginning of the group's most creative period, and is packed with unusual sonorities, including George Harrison's debut on sitar. On "Norwegian Wood" he plays it as if it were a guitar — more serious study was to come.

Lennon, too, began to appreciate what George Martin could do. "Like in 'In My Life', there's an Elizabethan piano solo in it, so he would put things like that in. We would say, 'Play like Bach,' or something, so he would put 12 bars in there. He helped us develop a language to talk to musicians," he recalled in 1971.

Working methods were changing too. When the Beatles arrived at Abbey Road, artists were supposed to wear collars and ties at all times in the building. They got rid of that, though the rule was kept for EMI staff for years to come. And then there were the working hours, strictly broken up into three-hour periods with an absolute 10pm curfew. By the end, the Beatles had taken up almost permanent residence in their favourite Studio Two, a long room with the control room up above.

But pressures within the band seemed to be becoming apparent too. For Lennon, Martin produced bright, clean balances, while for McCartney things were more bassy.

And then Lennon developed a distaste for the sound of his own voice, so that Martin was required to produce ever more elaborate ways of disguising it, ranging from the gentlest automatic double tracking (an EMI invention) to the wild excesses of "Tomorrow Never Knows". That track stands at one end of the 1966 Beatle aesthetic range: at the other is Paul's "Eleanor Rigby".

In between, keeping a balance that was both artistically successful and politically acceptable, was Martin. It must have been difficult in the extreme, but Martin is too loyal to say so. "They were never the sort of people you put in a studio to make three-minute pop songs with a nice arrangement; they needed much more than that and that was the real joy of working with them," he said.

To Martin, "Eleanor Rigby" is an extension of the "Yesterday" method, but here the vigorous eight-piece string chart is meant to recall the sinister film music of Hitchcock's composer Bernard Herrmann, author of the "Psycho" score among others.

Paul revelled in the flattery that Martin's exquisite arrangements gave his songs. His ballads became more unashamedly soft-hearted, his up-tempo material tending toward pastiche and parody.

John Lennon, meanwhile, was growing ever more cryptic and sardonic. His first offering for "Revolver", bearing the working title "The Void", may have been recorded just along the corridor from Cliff and the Shads, but belonged thousands of miles away in Lennon's acid-assisted imagination. On a lonely hillside in Tibet, to be precise.

"Often the backing I think of never comes off. With 'Tomorrow Never Knows', I had imagined in my head that in the background you would hear thousands of monks chanting. That was impractical of course and we did something different. I should have tried to get nearer to my original idea, because that was what I really wanted," he told Ray Connolly, a little ungratefully.

The instruction to come up with a sound like that might have worried lesser producers. But to Martin, it all sounded strangely familiar. "It was a kind of surrealistic look at building up sound pictures, which I thought was great, and was harking back to the Peter Sellers stuff," he said.

In the end what he did was to put John's voice through the revolving speaker of a Leslie cabinet, picking it up on microphones as it bounced around the walls of the studio. Then for the backing, Martin fixed up eight tape loops of assorted birds, beasts, backwards orchestras and electronic weirdnesses, each on a different tape machine, and then fed them back into a mixer so they could be played as if on an organ.

The whole ensemble sounded like the end of the world. But it wasn't. The Beatles and George Martin had hardly started.

Part two next month: Past the Pepper.