I recently found out of a special button somewhere in my car, that activated and deactivates the immobilizer for my car, sadly I can only activate/deactivate when in the car as I have no fob with a button to remotely do it but at least I know if I'm in a dodgy area I'll be almost safe in the knowledge my car won't be gone in the morning lol!
I'm insured with Highway through Adrian Flux and wasn't requested to prove immobilizer, only insured TPFT mind you.