A mate of mine who still works on the railways told me of the excuse he once used which, he claimed was absolutely true, when he was late for work.
  A bit of preinfo'.  Trains are fitted with AWS's [Advanced Warning System].  This is the thing you can hear on the small diesels ringing and blearing away everytime the train passes a signal. 
 Ring equal green, the blare is any other aspect. 
 Right then. 
 This mate of mine is fast asleep and his alarm clock goes off ringggggggggg.
 So, dreaming of driving a train (time to give up job I would have thought) he cancels it and carries on sleep driving.
 The snooze expires and ringggggggggggggg
 He cancels it and carries on again.
 Wakes up at a daft O'clock past his signing on for shift time, but goes in anyway.
 Train supervisor wants to know why he was late and sticks a form 1 in front of him for an explaination. 
 So, he wrote down as above. 
 He got away with it!!!  

 
  Ains.