Ooo Dear!
I never meant to tread on anyones toes with this, but I am afraid that events are already overtaking you Dave.
Sorry if that causes offence, it's not meant to. I just hate thieves and want to make their miserable little lives as hard as possible.
Like your system, mine too are resistant to bolt croppers and can be knocked up in the shed over a sunday.
What's more, if my contact in the trade does not wish to produce them I will be posting my drawings for free so that anyone can make them, as they really are pretty easy to make.
Not sure exactly what your system is or whether it is even remotely like mine, but I am doubtful that you could be able to put a patent on "a device to prevent Land Rover Discovery 2 Facelift headlights from being stolen". It sounds too much like trying to patent a car burglar alarm.
I suggest that you should seek advice from your local chamber of commerce before going too far down the patent route.