OK, so how stupid do I feel?

Pushed the pads back in all 3 calipers, but still struggled to push it round. Then I checked the bleeding obvious.............flat tyre on the back!!!. Spoke to the Mrs, she tells me that the local "Bob the Builder" was working at a neighbours house on Monday, and was tidying up the back of the van. I bet a screw or a nail from there was the cause of the problem. Thanks to all who contributed, at least this is an easy fix. I'll crawl back into the corner now and try not to waste your time again.