Jennie Harwood, the Rock Choir leader in Mansfield, Derby, West Bridgford and Beeston, was joined on stage by Rock Choir founder Caroline Redman Lusher, and her 80-strong vocal group in London’s Hyde Park.
Mansfield choral singers who attend weekly rock choir rehearsals were invited by the BBC to travel to Hyde Park and surprise the 40,000-strong audience.
Caroline and her group opened the event and also collaborated with Michael Ball, Josh Groban and Albert Hammond.
Jennie said: "I'm so proud of my choirs.
"Everyone came together and performed so magnificently in what was an historic and high-profile event created by the BBC.
"My Rock Choir members have said they had the time of their lives, it was an unforgettable experience for all."
Jayne Silverwood who was part of the Flashmob and a member of Beeston Rock Choir said: "The Proms in the Park was a truly remarkable experience. I can’t stop reflecting on what a fabulous time we had."
The choir flash-mobbed the audience during their first number, ‘Dancing in the Street’, while revealing their Rock Choir uniform t-shirts.
Rock Choir always welcomes new members to attend a free taster session.
There is no audition and no requirement to read music.
To find out more, visit rockchoir.com or call 01252 714276.