The excuses:
1. The traffic was terrible
2. The kids were playing up and they wouldn't get into the car
3. I had a flat tyre/battery and had to wait for the RAC
4. There was an accident blocking the road you use
5. There was a badger in the signal box at Woking (Ok I stole that one from Reginald Perrin)
6. Your pet cat/dog/budgie/hamster escaped and you couldn't find them
7. You forgot the report you were working on last night and you had to go back and fetch it
8. You were up so late finishing the report/proposal /Expression of Interest that you didn't hear the alarm (which works well with previous excuse)

The real reasons:
1. You hit the snooze button so many times you didn't get up in time
2. Your girl/boy friend stayed over and you were too busy fooling around to notice the time
3. You overslept - well it's true
4. You forgot to switch on the alarm clock in your drunken stupor
5. The accident you saw on the way to work was actually caused by you swerving in your lane when trying to put on your make-up/brush your hair/drink your coffee/eat your healthy macdonalds breakfast
6. And you decided to stop and take  a look.