1.   Just as this realisation dawned, a luckless couple drew into the parking space to read a map.

2.   She lay for several seconds trying to think what it was, then realisation suddenly dawned.

3.   For a second she gazed at them, perplexed, then realisation dawned and she made a single vain lunge forward.

4.   Then as the electric doors swished open and three police officers jumped out on to the ballast, the awful realisation dawned.