In a new BBC documentary, Boris Johnson revealed that David Cameron offered him a “top five job” during a tennis match to secure his support for remaining in the EU. Cameron, PM at the time, apparently wanted Boris to know that he: valued his contribution, that he would be a major party of the government going forward. Apparently, Cameron returned from the tennis match feeling “doubly good” after beating Johnson and believing he had appealed to his career ambitions. Nevertheless, Cameron was quickly outmanoeuvred when the then-London Mayor announced — “after a huge amount of heartache” — that he would support…