Tamora won't start - Laserline immobiliser problem?

[Litch]

My Tamora won't start after being laid up over winter. Turns over and fired then wouldn't run...fuel pump not working - checked fuses & relays per various discussion posts. I'm suspecting the immobiliser as the central locking's not working and I'm not getting the usual beep on ignition on. Looks like a previous owner had a Laserline unit fitted about 10 years ago. Tried pulling the immobiliser fuse and disconnecting the battery for a few minutes to reset but still no joy. Any suggestions? Is there a way of bypassing the immobiliser to confirm it's the culprit?

[Litch]

Looks to be a 213 - combined alarm (212) and immobiliser (921K) unit.