British group Clean Bandit stormed to the top of the singles charts with their dance pop tune Rather Be.
The track, featuring Jess Glynne, sold 163,000 copies over the last seven days, according to the Official Charts Company.
The quartet - brothers Jack and Luke Patterson, Grace Chatto and Neil Amin-Smith - knocked Pharrell Williams' Happy off the summit to score their first chart-topping single.
The group, who have become known for their fusion of classical arrangements with house beats, made their singles chart debut last April with Mozart's House which peaked at number 17.
The quartet came together in 2009 while Jack, Grace and Neil were studying at the University of Cambridge.
Williams slipped into second place, while pop rockers The Vamps entered the chart at number three with Wild Heart, their second top five single.
Girl group Neon Jungle's Braveheart came in at number four. Pitbull and Kesha's Timber slipped three places to number five.
British singer/songwriter Ellie Goulding returned to the top of the albums chart with Halcyon.
She reclaimed her crown from Bruce Springsteen's High Hopes, which fell a place to number two, having ended her two-week run at number one last Sunday.
Beyonce held firm at number three with her self-titled album, while Sophie Ellis-Bextor scored this week's highest new entry with Wanderlust at number four.
Avicii completed this week's top five with True, which climbed one place to number five.
US rockers Warpaint entered the chart at number nine with their self-titled second album, while Scottish band Mogwai came in at number 10.