Karen had no idea that the millions of viewers watching at home were actually in awe of the tear-jerking rendition they pulled off.
Meanwhile, the choir has performed a lullaby specially for the Duke and Duchess of Sussex's son, Archie Harrison Mountbatten-Windsor, who was born on May 6 .
Karen said: "It's a royal baby, so we touched on those words a little bit. But I think more than anything it's the blessing that we sing of the baby. 'May your dreams be high as the open sky, may your hope be filled as the ocean wide, as I sing you this lullaby.'
"To me those are powerful words and that's what we really wish and hope for the baby."
The group landed a Sony record deal as a result of the wedding and have been touring the UK, but they remain humble and Karen admitted that it's "weird" being recognised on the streets but still living a normal life and that she doesn't like signing autographs to friends and family because she doesn't consider herself to be any different to them.