The cream of British riders took part including Mark Cavendish, Bradley Wiggins, David Millar, Ben Swift, Daniel Lloyd, Jeremy Hunt, Roger Hammond, Rob Hayles and Chris Froome.
It was Froome who made the going in the 104 mile stage through the Welsh towns of Abergavenny, Monmouth, Blaenavon and Brynmawr.
His lead was three minutes before Cavendish who finished in the peleton, chased him down. House seized his chance and beat Froome to the line to take the win.
"It's phenomenal - a dream come true. I raced well and it was all down to me at the end. I'm speechless," said House to the BBC after the race.
British riders Mark Cavendish, David Millar and Bradley Wiggins will all compete in the Tour De France which starts on Saturday. We' ll have news of their progress throughout the tour.