If you can smell gas.

Four steps. In order.

If you can smell gas, run these in order.

Do not skip or reorder the steps. Turn off the gas at the meter only if you can do so safely and without delay; do not enter a cellar or basement to reach a meter there. Open doors and windows on the way out if it costs no extra delay, then leave.

1. 1

   STOP

   Do not turn any switches on or off, light a match, use a mobile phone inside or smoke. If you can do so safely and without delay, turn off the gas at the meter using its control handle. If the meter is in a cellar or basement, do not enter to reach it; leave the property.

2. 2

   OPEN

   Open doors and windows on the way out if it costs you no extra delay. Don't stop to fiddle — getting out cleanly comes first.

3. 3

   LEAVE

   Take everyone out of the property — including pets. Don't go back in for keys, phones or anything you can come back for later.

4. 4

   CALL

   From outside the property, dial 0800 111 999. The line is the National Gas Emergency Service, open 24/7, free from any phone. They'll guide the next steps.