Paul McCartney Pays Tribute to Late Wife Linda's Brother After His Death: 'He Was Unbeatable'

Ian Gavan/Getty Paul McCartney

Paul McCartney paid tribute to his brother-in-law John Eastman after his recent death.

On Thursday, McCartney, 80, posted to Instagram to share that Eastman, who was the brother of McCartney's late wife Linda McCartney, has died.

"My dear brother-in-law, John Eastman, has passed away. Having known each other for over 50 years it is an extremely sad time for me, and our families," McCartney wrote on Instagram.

"John was a great man. One of the nicest and smartest people I have had the good luck to have known in my life," he continued. "Not only did he help me massively in my business dealings as my lawyer but as a friend he was hard to beat."

Paul McCartney/Instagram John Eastman and Paul McCartney

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"His sense of humour always shone through in everything he did and his devotion to his family was supreme," McCartney wrote on Instagram.

Eastman entered McCartney's life when he married Linda, who died in 1998 from breast cancer at age 58. Eastman and his father, Lee Eastman, began representing McCartney during the Beatles' breakup and continued on to represent the ex-Beatle throughout his solo career, according to a biography on Eastman from New York University.

"We had so many fun times together through the years, but when the time came to be serious, he was unbeatable," McCartney wrote on Instagram Thursday.

"There is so much more that can be said of his incredible qualities, but words can hardly describe his passion for life and our affection for this amazing man," he continued. "He will be sorely missed but always held dear in the hearts of those of us who knew and loved him. See ya Johnny!"

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In June, McCartney welcomed special guests Bruce Springsteen and Jon Bon Jovi onstage for a jam session during the final tour date of his Got Back Tour at New Jersey's Metlife Stadium just before McCartney celebrated his 80th birthday.

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Springsteen, 72, performed his own 1984 hit "Glory Days" alongside McCartney before they delivered a rendition of the Beatles' "I Wanna Be Your Man," written by the stadium headliner and John Lennon, which was originally recorded by the Rolling Stones in 1963 before the iconic English boy band released their version on the With the Beatles album later the same year.

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Onstage, McCartney referred to Springsteen's appearance as a "birthday present to myself." Before performing "Glory Days," the Born in the U.S.A. rocker wished the former Beatle "80 more years of glory days."

That night, Bon Jovi, balloons in hand, came onstage to sing "Happy Birthday" to McCartney, and he returned at the end of the concert along with Springsteen to sing "The End" from the Beatles' Abbey Road album.