Hope the builders arrive soon and he's released (and the crab sticks cleared up!). Cats can be such sods, one of ours got stuck in a neighbour's garage for 5 days, the neighbour was mortified when she came back off holiday and realised he was stuck (cat was fine, but very annoyed). Sadly we can't cat proof our garden before anyone starts plus we're very rural and the cats roam the fields mostly.
Hopefully if your new neighbours have cats they'll see the funny side, I know I would (as long as I knew the cat was ok). We used to have one who would go through other cat flaps, but to be fair the cats from those houses would come into ours too. It's basically open house for cats here.