Garage Door Remote does not work with XK120 engine running

[Vanin]

The old XK120 has suppressed ignition leads and ends but it has a dynamo and a separate regulator.

Also has an electric fuel pump

Could any of these cause the interference that prevents the remote working. As soon as I turn off the engine it works perfectly

Aluminium bonnet somehow giving less shielding?

The remote works ok with the other more modern cars.

[12TS]

Could be any of them, but my guess would be the ignition.

Modern cars have to EMC compliant which should stop them emitting some of the frequencies that are used by the key fob.

[Jonmx]

They all do that sir....
As has been said above, the ignition may well be the culprit although I'm no expert.