In my house I put pooey nappies into one of those little plastic nappy bag things then put it in the kitchen bin. Sorry, didn't know it was illegal.

There is NO WAY I would put a pooey nappy into someone else's kitchen bin even though I do it myself at home. I would wrap it up and either take it home or put it in their wheelie bin (if I asked).

I would offer them a plastic bag (they can hardly refuse that) and then say "I'll pop that into the wheelie bin for you" until they get the idea and just start doing that themselves.