Sir Paul McCartney has paid tribute to Sir George Martin, the record producer known as the Fifth Beatle who has died aged 90, calling him a "true gentleman and like a second father to me".
The producer's family revealed he passed away at home on Tuesday and thanked "everyone for their thoughts, prayers and messages of support".
Sir George's son Giles, who is also a producer, tweeted: "RIP dad. I love you. I'm so proud to have been your son. I'll miss you more than words can say. Thank you for the all times we had together."
In a statement, Sir Paul said: "I have so many wonderful memories of this great man that will be with me forever. He was a true gentleman and like a second father to me.
"He guided the career of The Beatles with such skill and good humour that he became a true friend to me and my family. If anyone earned the title of the Fifth Beatle it was George.
"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."
The news was confirmed early on Wednesday by another Beatle, Ringo Starr, who tweeted: "God bless George Martin peace and love to Judy and his family ... Thank you for all your love and kindness George peace and love xx."
:: Sir George Martin: Tributes To A 'Visionary'
Sir George's long and successful career began in 1950 after he concluded his studies at the Guildhall School of Music, and worked as a professional oboist.
Sir George became head of the Parlophone music label in 1955, and went on to sign The Beatles in 1962, enjoying 17 chart-topping hits with the band.
He recalled meeting the quartet for the first time and realising their potential.
"I liked them as people apart from anything else, and I was convinced that we had the makings of a hit group," he said.
But he was not convinced they had songwriting ability.
"As composers, they didn't rate. They hadn't shown me that they could write anything at all," he told Melody Maker.
"Love Me Do I thought was pretty poor, but it was the best we could do."
Sir George also composed scores for the Beatles films A Hard Day's Night - which he received an Oscar nomination for - and Yellow Submarine, which was nominated for a Grammy.
After the group broke up, he started his own music publishing company and set about working with other artists.
Sir George worked with the likes of Jeff Beck, Bob Dylan, Sting and Sir Elton John and recorded two of Sir Paul's solo albums, Tug Of War and Pipes Of Peace.
He co-produced Sir Elton's Candle In The Wind, which was released to mark the death of Princess Diana in 1997, and the song sold 37 million copies.
Sir George was also behind a string of humorous records and novelty hits which went on to enjoy a long shelf-life on light entertainment shows.
The Queen awarded him with a CBE in 1988 and he received a knighthood in the 1996 birthday honours.