As ds got off the loo, he screamed, and his toilet seat fell sidelong into the loo. The top (padded) part of the seat is held onto the bottom (hard plastic) by 3 screws. On our seat the screwholes were too big, the screws did not grip and the seat parts twisted when ds got off. This left two sharp screws sticking up, one of which pierced his bum (not too deeply but enough for him to be quite upset about..and he is now only happy to use the potty not the toilet again).
Thought I'd warn anyone who has a similar seat to check how firmly the two parts are attached..Mine's going back to Mothercare as soon as I can.
It's this seat here