just to add a cautionary tale - I was getting a new UPC box recently and a guy was with the UPC man, I assumed he was with him (which I thought was overkill for one box!)
It was only when he gained access to the house that he said he was there to check out the household charge - the UPC guy (who had ID etc) told him to prove it, and he went and ran away. If I'd been on my own/elderly I would have fallen for it. Simply coincidence that they both turned up at the same time - or actually was it, do criminals do this as they reckon you will only ask for one id?