From the BBC we learn:-
Jumble sale jam makers could face new scrutiny - after it emerged they might have been flouting food hygiene rules.
Homemade preserves sold in fetes are often stored in sterilised used jars.
But a parishioner in the Diocese of Peterborough, which covers Northamptonshire and Rutland, was made aware of hygiene rules which state only new jars should be used.
Peterborough City Council, which has the power to enforce the rule, said it would be discussing the issue.
Jams can only be sold in used jars at special events and with local authority permission.
My parents were keen jam-makers, especially at this time of year when the fruit harvest comes in. They would never think of buying new jars though - we recycled in those days you see. However, in later years when they were getting on a bit, we were given a jar of jam with a label like this still stuck to the jar:-
For some reason we decided not to eat it.