We've heard all sorts of excuses for rail delays, from the wrong kind of leaves and even the wrong kind of snow.
But the wrong kind of bird on the tracks is a new one on us.
But the video above shows the moment a train was delayed because it was forced to crawl along behind a stubborn swan waddling on the tracks for a staggering two miles.
Commuters got into a right old flap when the train from Teddington was forced to slow down to a snail - or a swan's - pace after leaving the station.
See also: Mystery as 20 swans die in same stretch of UK river
See also: Cambridge swan invasion: People feeding them bread to blame
This video shows the bird waddling along with the slow-moving train just a metre behind as it pulled into Kingston station more than two miles away.