Programming 307 key.

[The Mackem]

I'm looking for a how to programme a 307 remote to the ignition. I've just swapped over the housing as the old one was worn. The key still locks and unlocks the car but won't start it. I've tried the method in the 307 manual which is

Switch off the ignition

Switch the ignition on again

Immediately press button A

Switch off the ignition and remove the remote control key from the ignition lock. The remote control is now working again.

Many thanks in advance for the help.

Rob.