A diary written in 1969 by the wife of "the Fifth Beatle" which sheds new light on the Fab Four's break up has sold to a fan at auction for three times its estimate. 

Joan Taylor documented the demise of The Beatles a year before they officially split while married to Derek Taylor, the band's press officer and close friend. 

She kept entries which recorded arguments between the hitmakers, showing how cracks were beginning to show during the fraught period of early 1969.

The diary is scathing of Paul McCartney with Joan detailing a "rotten day with Paul" and "More trouble with Paul Mc" leading to "sleepless nights" for her husband.

One entry even reveals the moment George Harrison seemingly quit the band - "George has walked out of The Beatles and won't go back."

She also touched on the introduction of notorious recording boss Allen Klein who is said to have influenced The Beatles split.

It reads: "Allen Klein going to handle business affairs for The Beatles, which has put the cat among the pigeons."

Auctioneers said the diary gave a unique first-hand look at the events leading up to the break-up and a fascinating insight into their personal relationships and business life.

It was given an estimate of between 400-£600 and sold for £1,875 at Special Auction Services in Newbury, Berkshire, on Tuesday, March 26.

SAS director Thomas Forrester said: "This is a great example of how the Fab Four still remain current in such a modern world.

“We had plenty of interest from Beatles collectors and we're very pleased the diary was sold to a fan."

Derek worked at Apple Corps as the band's head of publicity at the height of Beatlemania in 1964 then again between 1968 and 1970.

He was one of several associates to earn the moniker "the Fifth Beatle" and he was the man who confirmed the Beatles break-up after Paul hinted the group was no more.

His wife's diary also includes day-to-day details such as taking delivery of John's piano and having 'good nights out' with him and Yoko in happier times. 

Joan wrote: "We came home with John, Yoko and Pete and played records and smoked.

"John and Yoko are buying a house in Virginia Water."

But later entries describe Derek coming home from work exhausted and having sleepless nights, which spelt "the beginning of the end."

Derek was close with George Harrison but less so with Paul McCartney which is evident in some extracts.

One reads: "More trouble with Paul Mc, it went on most of the day and night.

"Pattie bought Derek home after visiting George in hospital. 

"We are both pretty exhausted by it all. I think this is the beginning of the end for Derek at Apple."

Another says: "Derek is having a particularly difficult time at the office as a result of John's interview on disc.

"We had a bit of bother on the phone. George came for a chat and when they came home it was all OK but they looked wacked."

A further extract reads: "He has had a rotten day with Paul and another sleepless night."

Another details the arrest of George and Pattie Harrison when police carried out a drugs bust at their home on March 12, 1969 - the day of Paul McCartney’s wedding.

It reads: "George and Pattie were busted this afternoon. Derek went with George to the police station." 

Dave Martin, the auctioneers' music and entertainment expert said ahead of the sale: “The Beatles have been written about so many times that it is hard to find new insights into the band.

"But this diary throws a light on the key dates and events in the run up to their split and gives personal details that would not have been available before. 

"Although the public were not aware of it, the break-up was building up for about a year before it became public, and so to a Beatles collector this is a fascinating artefact.”