Who was Mr Mustard?
Mark Lewisohn has done extensive research into the back=story of former civil servant Mr John Mustard. This certainly not the case with Lennon who seems to have been a little embarrassed about the the source. In on of his last interviews he describes Mean Mr Mustard as 'garbage'. Earlier he had referred to it as 'just a piece of crap I wrote in India.'
This dismissiveness is perhaps partially the result of his frustration of being unable to finish the song. It would be two years before it was completed and found a home in the medley on Abbey Road. To do this Lennon built in a link with Polythene Pam by changing the name of John Mustard's siser .
An alternative theory about the song's origin is provide by Tony Barrow. He suggested that it was inspired by 'an old ‘bag lady’ who used to hang around the Knightsbridge end of Hyde Park, London,' This seems implausible given that the song focuses on meanness rather than vagrancy