Ratings leapt to 4.5 million - an 18 per cent share - this week, up by more than one million viewers on the previous week.
Carphone Warehouse has rejected reports that it was considering pulling its sponsorship and agency broadcast directors are applauding the ratings.
Chris Locke, the group trading director at Starcom, said: "It's fantastic news for Channel 4. I wouldn't be surprised if ratings rise to six million as people look to see what the fuss is about. For Carphone Warehouse, this is a Kate Moss moment."