Ford Focus Central Locking/Starting Problem?

Hi, my father in laws Ford Focus failed to start last night. On opening the car on the remote, the rear door locks make a clunking sound. When the key was put in the ignition and a start attempted a rapid clicking was heard and some panel lights flashed but no turning of the engine. I also noted the immobiliser control unit(?) clicking in the footwell. Several attemts made but no joy. Suggestions please? I am suspecting a latching relay of some type failing or sticking in the starter/central locking/immobiliser circuit preventing enough current being permitted to the starter solenoid/motor. I am guessing as I have no circuit diagram!