It would seem to be simply a badly adjusted hand break which is going to end up costing me a bundle.

What you actually have is a handbrake that you did not apply correctly.

I started driving in 1974 and was taught to always leave the car in gear and if on a hill point the wheels slightly into the kerb if facing downhill and away from the kerb if pointing uphill. In my time I have had some rubbish handbrakes but never had a runaway.

That is unlucky, but I think it's one of those things that is bound to happen eventually if you rely solely on the parking brake.

I usually leave mine in gear and always have done; but in 1992 I left an Audi 100 with only the handbrake set and it trundled off into a wall.

I put it down to the handbrake acting on the rear disc instead of a drum. Any contraction going on as it cools can only reduce the clamping effort. Many rear-disc-braked cars now have a separate drum for the handbrake, but I don't think that one did.

Indeed - A work friend had the same issue a few years ago -with a new Seat Leon rolling from a car park , over a road and into a wall!

Same thing - contraction of the brake disk on cooling released the handbrake

Bought my first car with rear discs in 1986, a Golf GTi. Since then over about 500,000 miles the wife and myself have had a total of 9 cars with rear discs. How many runaway incidents, a big fat ZERO. Apply the handbrake fully and leave the car in gear has worked perfectly for us.

Cars can and do have mechanical failures but a huge majority of these incidents are simple user error.

Recently 8th generation Civics had a recall on handbrake mechanism assembled incorrectly.

I remember that Vectras had a problem with handbrakes letting go-in fact I saw one do it when it was parked on the street, ran over tried to stop it as it was slowly creeping downhill-went and banged on the house door and the bloke came out and said I've just got back from the Vauxhall dealer who have supposed to have fixed it!