Being a Dad, I have an instinctive knowledge of what out-of-date foodstuffs are basically safe to eat.
Chocolate, for example, is always fine. It might get that dusty white effect but it'll do you no harm.
Crisps will always be fine. They might even taste a little soft and stale which will remind you of your childhood when crisp packet technology was more rudimentary and all crisps tasted like that most of the time.
But an out of date packet of M&S prawn crackers has flummoxed me. Thoughts?