Could you imagine facing Boris Johnson in a cage fight? Well, in 2012 when Johnson was Mayor of London, in a mischievous moment when he was being irritating, I offered him out one night at a drinks reception in central London.

"I'm challenging you to a cage fight... fancy it ?" I said to Johnson. Lo and behold, in a nano-second and without any hesitation, Alexander Boris de Pfeffel Johnson gave his riposte.

"I fight at 217 pounds [15st 5lbs]. When and where does it go down?" the floppy-haired blonde replied, looking me square in the face from behind those droopy eyelids and without a hint of flimflam. He looked a good stone heavier.

We nodded at each other as if in accord and off went Johnson to schmooze the room. It was around the time of the London Olympics and Paralympic Games, and Guto Harri - the BBC's former chief political correspondent - was Johnson's Director of Communications. "Is he serious?" I asked Hari. "He might well be," he replied. "You never know with Boris."

But maybe it would not have been so unusual if Boris the politician had indeed gone ahead with the fight, for charity or whatever cause that might have been the excuse for "fisticuffs" - as Johnson calls boxing.