I've got a very similar situation with a neighbour. He and his wife arrived in the village about 10 or so years ago and another neighbour bounded round in great excitement telling us that the newcomer was a retired airline pilot. When we first visited, the conservatory was full of those airliner models like you used to see in travel agents and naturally we asked who he flew for etc. Seems he'd been at various times a copper, a lorry driver, a coach driver and then latterly, had come into some money, paid for his training and got a job with Monarch, retiring early due to some health problem. He made a great thing about how he had met his current wife in a bar whilst dressed in his 'Captains' uniform.
Now we listened to all this stuff for a couple of years but as in all these cases, the longer it went on, the more it got embellished, up to the point where he apparently was captaining the the last transatlantic plane to leave US airspace after 9/11 shut it all down.
The thing is, he seems to know a fair bit about routes, cabin fits and the different aircraft variants but he's evasive when you get into the nuts and bolts of flying. As it happens, I let on fairly early on that I had done some powered flying towards a PPL and another neighbour has his. This didn't seem to put the bluffer off although when I dropped the odd technical question into conversation, he had a habit of changing the subject quickly. What did it for me was when a hot air balloon went over one day and he read the registration out loud as (something like): G - ABC1 (as opposed to G - ABCI). When I pulled him up on this, he just said that he'd forgotten the registrations were all letters!
Another colleague raised doubts openly and asked to see photos or a log book. The excuse given was that there had been a burglary at a previous house and all the stuff had gone missing.
It's got to the stage now where I don't bother about it any more and as some have said here, why 'out' him?, but it does rather annoy me that he persists, even though he must know the game's up as far as I'm concerned. I've seen the Army site where they pursue the 'Walts' mercilessly but I suppose when you've risked your life for Queen and country, it's a far greater insult to have imposters saying they've done the same. Also, it's easier to check the service and medal records and get absolute proof of deception.
At least he hasn't gone the whole hog and tried to con his way onto a flight deck....so far....