I've had one engine failure - at the hold prior to departure....
The story echoes what has already been said; if anything doesn't seem right then check again.
First indication was engine run-up during power checks gave a few fewer revs at full throttle than usual (about 4% down). I might not have noticed without the digital tacho that is fitted in addition to the normal rev counter. Rechecked everything in cockpit and tried again - same result. Taxied back to parking, engine covers off, plugs out, throttle cable check, all looks ok. Perhaps I've imagined it! Re-assemble, return to hold to do power checks. All ok except max rpm still about 4% down. Decide to keep full power on for a few minutes to see if it clears. No change for a few minutes, followed by revs dropping even more. Just as I'm wondering why, engine stops dead with a broken crank.
VERY pleased I took notice, congratulate myself on purchase of digital tacho. Relief at being all in one piece with intact airframe helps overcome financial shock of engine repair. Arrive home safely and explain why I'm back so early. Mrs QNH not impressed and brownie points and beer tokens fall to all-time low.