Thankfully he hasn't yet been paid so the account is empty. I did say that with it being a contactless card, if the people who purchased our old house aren't trustworthy they could use it but the man at Nationwide replied that to use it they'd need to verify it with the PIN number...to which I added "and you've also sent that to the wrong address haven't you". He sheepishly agreed that they had.
Oddly enough, the same happened with John a year or so back but with Barclays that time. He'd been receiving all correspondence and even new debit cards at this address since we'd moved when for some peculiar reason their system decided to revert to the old address when sending out his most recent card.