I remember well an occasion 15 years or so ago when we were told by driver our train into London would be delayed due to 'sheep on the line'. There was much incredulity as you can imagine when we were a couple of miles inside the M25 which is very urban. The Driver said over the tannoy that he didn't believe it either and took the micky out of his own company for covering up for a points failure or similar. After a long delay when we got to the place of the trouble, there was indeed a small flock of sheep on the rails about 3-400 yards outside of Liverpool street station. Never did find out where they cam from.
