Quite a few over the years but one stands out as an interesting case study of the tiny margins of error available to ATC at busy airports.
I was jumpseating on approach into Gatwick a couple years ago and as we were transferred to tower, we were #2 for arrival about 7 miles behind an EZS 319. Meanwhile, there was the usual morning line of EZY 319s waiting to depart.
The leading EZY 319 at the Juliet hold received clearance "after landing traffic line up and wait 08R" with the EZS 319 on short finals. They proceeded to do so as the EZS touched down and rolled out. Unfortunately, the EZS rolled too long and missed his planned taxiway exit. That delayed the takeoff clearance for the departing EZY 319 now sitting stationary over the numbers. You could hear the frustration in the controllers voice as he instructed the EZS to "expedite exit left contact ground 121.8". Meanwhile we are now right at 1000 ft and the EZY 319 hasn't even rolled.
Our captain was on the ball and was already anticipating a go-around by this time. Sure enough, the instruction came from tower a few seconds later and he immediately retracted the gear and applied TOGA power. It was an incredible experience to fly along the runway with the gear retracting at just a few hundred feet and then break off back to rejoin the pattern.
20 minutes later we were back on finals with the same controller and he apologised for the situation. Not his fault though and can't really blame the EZS either. Just one of those cases where the ducks didn't line up at the right time. If the EZS had been 5 knots slower he could have made the turnoff. If we had been 30 seconds behind there would have been enough time for the EZY to roll and rotate before we touched down. None of this could be reasonably forecast when the instructions were given to line us up the way we were but introducing longer spacing would reduce the flow rates too far below capacity to be practical. Just another day at the office for the Gatwick NATS team who are one of the best in the business....