This is the episode about those big lads with heads squashed flat and brains curdled into early onset dementia by the constant heading of old fashioned leather footballs that weighed the same as a cannonball after it had been soaked by rain and coated in mud.  From the time that Herbert Chapman withdrew the middle of the half backs to play between the two full backs we always recognised the centre half as the bulwark of the defence.  Paddy Barclay, Jon Holmes and Colin Shindler discuss the way in which these immobile centre halves became more sophisticated until we got the emergence of the skilful and mobile central defender who can now attack and defend with equal facility. Learn more about your ad choices. Visit podcastchoices.com/adchoices