Hi there all – have searched and searched for this. I think it’s a 60’s or 70’s foreign (French?) possibly black and white film. My memory is that a guy has set up a booby trap to cause an explosion & opens the gas tap, leaving a lit candle in a candlestick on a sideboard. The theory is that the gas will build up and when the level reaches the candle flame, there will be an explosion. Anyway, in closing the door to leave the room, the draught extinguishes the candle and the gas just goes building up and up. Some time later, a guy (possibly a postman? wearing a cap?) comes to the door (to deliver post???) smoking a cigarette. He bends down to open the letterbox and Boom!
That’s all I remember. I think it was one of those old French houses with shutters but I could be imagining that. Heck, I could be imagining the whole thing.
I think it was one of those foreign films shown on BBC2 in the UK late on Saturday evenings in the 70s. I learned a lot from those films.