Ok,

After another look, I found the following:

Fob sends a signal to a receiver (Z87/15) behind the dash near the airbag, this connects to the radio frequency DAS control (N54/3) via terminals 6&7. DAS control is behind the instrument cluster. DAS then talks to the bcm, which then talks to the PSE control module (air pump assembly), which then signals the indicators to flash and send air to the relevant locks.

Lyndon,
I know you've checked the PSE in the boot and it seemed ok. Did you pull the multiplug connectors off it and have a look at the terminals? That PSE appears to carry out more functions than we may give it credit for. In saying that, I'm still suspecting that the fob may not be sending out a signal to the receiver.