That's not something you want to wake up to, you have my sympathies. It's hard to miss so l'll keep my eyes open.
I would imagine it was lifted as they're a bit difficult to take for a joyride but there are still plenty being broken so why take it for spares?
I never really worry about mine overmuch as they're well protected & l tend to think, who would nick it anyway?
Mind you, l think the MG's might have a bit more of a cachè than the Rover's among certain demographics and these days with cars being stripped of panels & spares where they're parked overnight who knows what the skroats are after at any given time.