....Which still neatly avoids the obvious observation that you, the owner, nor the insurer will 'know' for sure how many keys the vehicle should have.
Here is an example.
My bike has three keys and a plastic one, total four. All four will I assume be logged with BuMW, who supplied them. I have never told my insurer, as they have never asked, how many keys I have nor how I came to have four.
After three years of ownership I lose the plastic key somewhere, when I lose my wallet. I do not inform BuMW nor my insurer as I am not obliged to. I now have three keys and BuMW think I have four. My insurer still has no idea how many keys I have.
After four years I then run over one of the metal keys. It still works but the rubber tag has ripped, meaning it cannot be held on a key ring. I throw it away. Again, I am not obliged to inform BuMW or my insurer. I now have two keys but BuMW still think I have four and my insurer still has no idea how many I have.
After five years I sell you the bike, giving you the two keys. How many keys do you think is the 'right number'?
Would your answer change if I simply gave you one key? Knocking £50 off the bargain price, so you could buy another if you wanted to?
How many keys will you tell your insurer you have? The answer to that question is, you won't tell them as they won't ask.
Your example of the car being stolen when left ticking over is possible, it will depend on the wording of your policy. But its invalidation is dictated by the circumstances of the theft, not by the possible number of keys in circulation.
You have an obligation to tell the truth when submitting a claim. You are obliged to tell your insurer that you left the car ticking over, with its key in the ignition, whilst you had a dump (or whatever it was you were doing).. That may invalidate your coverage, read your wording.... It is most often seen when bods leave their keys in the ignition when paying for petrol.... or when an innocent bod hands their key to a theif who drives off on a test ride, never to return.
Of course you could always say that it was stolen whilst you slept and it would be up to your insurer to prove that it wasn't, but that would be fraud on your part.
