But the middle-aged Eton and Oxford contemporaries showed that any alliance between them will always struggle when they promptly lost the game.
The prime minister invited the London mayor for lunch as a friendly gesture, though there was an element of calculation. Johnson overshadowed Cameron during the summer as he lapped up attention during the Olympics. Team Cameron are expecting Johnson to try to capture the limelight at next week's Tory conference in Birmingham.
With this is mind, Cameron took Johnson and his family to his favourite lunchtime pub near Chequers. This was the pub where the Camerons recently drove off without their daughter Nancy.
One Tory source said: "There was no tennis but there was an adult versus kids football match, which the kids won. They are politically totally united, particularly so against Labour."
Cameron is hoping to use his charm to embrace Johnson, who upstaged him at the Olympics and Paralympics parade. The London mayor has also launched a series of aggressive attacks on Downing Street over the weakening of its opposition to a third runway at Heathrow.
Johnson, who has not been able to accept an invitation to Chequers until now, was understood to have been on his best behaviour with the Camerons. But he has no intention of abandoning his ambitions to replace Cameron as Tory leader.
Johnson regards Cameron as intellectually inferior and a less skilled politician. He believes that his success in winning two successive elections in a predominantly Labour city on a centre-right ticket provides the model for a modern Conservative. He is dismissive of Cameron's attempts to reach out beyond the Tory party, only to pander to its base.
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