Olly Murs wishes he "could have done more" at the Coronation concert on Sunday.
The X Factor star, 38, joined a star-studded line-up to perform his smash hit, Dance With Me Tonight.
The Royal Family looked like they were having a great time at the gig, but Olly left the night with regret.
Taking to Instagram, he said: "Just leaving Windsor Castle after party, mingling with the royals.
'It was fantastic. Got to meet some absolute legends. Honestly thank you all for all your kind messages - I've seen it all, I've just been on social media now and just thank you for all your lovely messages about my performance.
"I loved it! Wish I could have done more. But what an honour it was!"
The Voice star continued: "I am off now for the next couple of weeks and I'm going to enjoy myself at home with Amelia and the dog and just have some me time!
"But what a way to end the last couple of weeks by doing this. I loved every minute of it and I'm proud."
Twitter fans loved Olly's performance with many saying the singer outshone Katy Perry and Lionel Ritchie.
He certainly looked the part in a pair of cream chinos and a blazer, but some viewers couldn't get over his 'bizarre' accent.
One asked: "What's with Olly Murs and the bizarre American accent??"
While another mused: "I love Olly and I know he sings in an American accent but he's at the KING OF ENGLAND'S Coronation guys."
Olly was interviewed before his performance where he sang in front of the newly crowned King and Queen - as well as 20,000 people.
Explaining how proud he was to have been asked, he said on BBC Radio 2: "It's a bit surreal but I am so honoured. I am on tour at the moment so only yesterday I saw the stage. It's the biggest thing in my career.
"It has the eyes of the world on it. This is something people will remember. It is really special. It's crazy. We just got an email asking me to do it!"
However, something Olly promised he wouldn't do was take his shirt off, joking: "I have to be professional."
The star has a big summer coming up as he plans to get hitched to his bodybuilder girlfriend, Amelia Tank.
Taking to Instagram recently sharing a snap of the pair, he wrote: "Our last holiday as Mr and Miss.. very exciting 2023 ahead for many reasons the tour, more music, starstruck season 2, the voice and of course the wedding!"