I'm not being daft but I always feel it's a cop out when they won't pay due to the key situation. Did you give him permission to go for a spin in your van? No! End of. Still theft IMO bit more involved if they didn't catch him as obviously your mate could have pinched it for you blah blah and all the stuff they would accuse you of
I have a customer with a large collection of cars which all have to be left with keys in by order of the insurance company incase of a fire and how long it would take to find each key and get them out to safety
They choose the rule that suits 'em