Had it happen in a Tiger Moth, the non-return breather on top of the tank has corroded closed. Impossible to detect from the outside - short of sticking the gob on it and giving it a blow.
After an engineers inspection it was assumed the engine failure was due to carby ice, i agreed, given the conditions on the day were perfect for it. Of course she started up beautifully after we had opened the tank a few times! Thankfully the owner of the field was nice enough to let us slash a strip and out I flew.........5 mins later........ I learnt a lesson that day
The second farmer was just as nice, though she got trucked home.... I walked.
Ironic really, the Tiger's the only aircraft i've flown where checking the breather isn't part of my Pre-Flight, mainly because of accessibility.......it is now.