ldv convoy no ignition, lights, starting?

Have an 03 ldv convoy minibus at work, that doesn't work!
it cut out and now has no lights, ignition or starting. no dash lights etc.
have 12v at the brown wire on the back of ign switch but not the others. as soon as turn ign on no power at all at back of switch.
all fuses ok, no feed to ign fuse at dash,
immobiliser light in centre of dash flashes.
any ideas? have seen all the immobiliser problems online but they all seem to keep dash etc working.

thanks

j