I remember being told or reading somewhere that Peas Pottage (the village south of Crawley) was called that because that what was given to prisoners being taken to - I can't remember which - Lewes Gaol or perhaps Horsham. Pois cassés is still a dish eaten in France today - it's a thick broth of mashed peas.
There used to be a nice pub there, but I hear they've closed down the brewery, but I'm guessing that it might have been the building where they fed the prisoners. Whether the rhyme has anything to do with the place, I have no idea.