Glad all is OK Stu, good job nothing else happened whilst on the hard shoulder.....
A friend of mine recently told me a similar story. His car was a Mondeo I think; he and some friends went walking in the Peak District. He parked up in a public car park, and left the car running whilst using the boot (not sure why - probably the beer cooler), but after they all get thier walking boots on, they just shut the boot and walked off.
When they got back, he was surprised to see the car still there, still unlocked, and still running..........about 4 hrs in all. At least the beer was cold.