Thanks Yorkie!
It had been suggested for the soil, but it was only one very small patch well away from everything else, so I wasn't going to bother. Anyway, there are hellebores in there
It's just possible there isn't white rot! The gent told me nobody used the compost because all sorts went into it and it never got hot enough to kill things. So it's just possible I got away with it. Still want to clean off the things I used though.
I just wish someone had put a sign on it saying "Do not use"
Then again, I didn't either