"A walker taking a short cut through a farm yard bumps into the farmer, accompanied by a pig with a wooden leg. ‘What’s his story?’ asks the walker. ‘That, my friend, is Lancelot,’ replies the farmer. ‘He can do arithmetic. What’s four plus three, Lancelot?’ The pig stamps his wooden leg seven times. ‘What’s two plus one?’ Bang bang bang!

‘And what’s more,’ says the farmer, ‘he’s a life saver. My little daughter had fallen into a pond and was on the verge of drowning when Lancelot dived in, grabbed her by the scruff of the neck and pulled her to safety.’

‘Blimey,’ says the walker. ‘And what about the wooden leg?’

‘Well,’ says the farmer, ‘you don’t eat a pig like that all at once."