1. Find a working car and jump leads. Ensure that the battery terminals are securely connected to the respective batteries.
2. Park the working car next to, BUT NOT TOUCHING, the broken one in such a way that the batteries are as close as possible... ie if the working car is the Omega, so that the nearside wing is next to the Vauxhall badge on the Vectra Grill.
3. With both cars off, connect the red lead to both positive terminals.
4. Connect the black lead to both negative terminals, starting with the working car.
5. Start the working car, and leave to idle. Then turn the headlights on.
6. Only now should you insert the key on the broken car.
Turn to position 1 and count to ten.
7. Turn the key to position 2 and count to ten.
8. Try cranking the broken car.
9. If it starts, allow both cars to idle for five minutes. Then with both cars idling, disconnect the leads in reverse order.
10. If it cranks but doesn't start, repeat 6/7/8.
If it doesn't crank, then you'll need to get someone to have a look at it.