I really must remember to check profiles before making assumptions about gender! (Even then I could still get it wrong, I suppose!). I think I made my error simply because I'm so used to seeing the term 'OH' used frequently by the ladies on here (such as Caran) and very rarely by the men.
Googling
"activity key" "car" '"insurance"
only seems to bring up references to the new Jag, so I was unaware that any other vehicle had the system.
There's absolutely nothing wrong with having a nice car. Assuming that you were referring to a Jag, I was just thinking about the very high costs of running one!
Anyway, my advice still holds. Your OH really needs to check with her insurer, preferably getting something in writing (or, at the very least, noting down the date and time of a telephone enquiry), so that she can be sure that she's covered if the worst happens.