The Prime Minister and Olympics chair Sebastian Coe joined a group of young badminton players for a game in the Downing Street garden.
Strolling onto the pitch in a crisp white shirt, Mr Cameron was heard to say: "I don't know the rules". Some of the younger players, who were there to launch the Sainsbury's School Games competition, helped demystify the game.
All players soon got into their stride managing some relatively long rallies, despite some shocking misses from Cameron and Coe.
The two younger players kept a low profile, allowing the rivalry between the two political allies to bubble to the surface. At one point the Prime Minister uttered "I want to beat Seb, you know?"
No-one noted the final score - it was a 'friendly' game after all - but it wouldn't have surprised anyone to learn that both Cameron and Coe were counting.