The 'Hello' hitmaker, 34, rejected the invitation while 'The A-Team' singer Ed, 32, found it "difficult" for him to perform at the May 7 show at Windsor Castle due to his gig in America, reports aceshowbiz.com.
The Sun reported on Sunday that Adele has nothing publicly scheduled for May 7 or after March 25 when her Las Vegas residency is set to end, but she is apparently "locked in to other commitments that will prevent her from attending."
"There is a team set up to get the talent signed up but they were unavailable, which was a massive disappointment. They are titans of the showbiz industry and are quintessentially British but also known across the globe. It's such a shame."
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Sheeran is scheduled to appear at a show in Texas the day before the coronation show, and insiders told the Mail on Sunday that even though it would make it "difficult for him to get to the Windsor show" he could still "make the nine-hour journey in time by private jet."
The singer closed the late Queen's Platinum Jubilee Pageant in June 2022 with his hit 'Perfect', chosen as a tribute to the then monarch and her late husband Prince Philip.
King Charles, 74, is said to want Harry Styles, 29, to play the show while Lionel Richie, 73, is said to be close to agreeing, as are the Spice Girls.
(Los Angeles, IANS)