The Military Wives' choirmaster described the group's prize win at the Classical Brits as "the candle on the icing of a very large cake".
The choir scooped the single of the year gong for their Christmas chart-topper Wherever You Are at the glitzy ceremony at London's Royal Albert Hall.
The group helped to round off the evening by performing another hit, the Diamond Jubilee anthem Sing. They were accompanied by the song's composers, Take That star Gary Barlow and Andrew Lloyd Webber who both played grand pianos.
Choirmaster Gareth Malone said: "It was very humble beginnings. It is about these women finding a voice and tonight is a great celebration of that."
Members of the choir, made up of the wives and girlfriends of military personnel, rubbed shoulders with the likes of Sir Anthony Hopkins at the event. The Oscar-winning actor attended the awards alongside Dutch maestro Andre Rieu, who picked up the prize for album of the year for his interpretation of a waltz Sir Anthony wrote many years ago.
Rieu - known as the king of the waltz - dedicated the award to Sir Anthony and said: "He is the greatest actor we have now on this planet. Tony, thank you for this fantastic waltz and thank you for your friendship."
Speaking backstage at the ceremony Sir Anthony insisted the win was all down to Rieu and said: "I'm just here by happy accident."
Guests at the event - officially called the Classic Brit Awards 2012 with MasterCard - were to include the Duchess of Cornwall but she had to pull out due to a middle ear infection and sinusitis.
The 20-year-old pianist Benjamin Grosvenor became the youngest ever male winner at the event, taking the critics' choice prize. Russian conductor of the Royal Liverpool Philharmonic Orchestra, Vasily Petrenko, took the best male artist prize for his work on five albums.
Violinist Nicola Benedetti was handed the award for top female artist for her album Italia. US composer Williams achieved his lifetime achievement honour for orchestral scores for dozens of well-known movies, including Jaws, Superman, the Harry Potter series and Star Wars. His best composer prize recognised his work on War Horse and The Adventures Of Tintin during the past year.