Thank you very much.

It wasn't exactly an incrementation problem.

I only had one form on the page I was generating, because I didn't realise that you could have more than one.

I've now put in one form per button, so the hidden ID field is different for each one, and it works wonderfully.

Hmmm, now I've got the search producing a list, and a detail page successfully, I need to learn how to update the data, but that's another thread!

Next time I have a question (which won't be very long!), I shall make sure to include the relevant code. :-)