I remember a documentary about a chap who dresses in a suit (so that he is respectable for going into the 'big houses') and cycles round with a grinding wheel attached to his bike and sharpens knives. Can't recall the girlfriend though. It was one of those films about individuals which touched your heart.
Again only a vague memory but wasn't there a documentary film maker who specialised in this sort of film who died in the last 5 years or so and there was a programme about him and his documentaries.
Not too sure whether it helps but like you the knife grinder is in my brain.
Freddy