I know of someone who got the blame for an accident as he had parked his car on double yellows on a corner before.
In this case it was a head on between 2 cars and both parties agreed that the fault should be put on the driver of the parked car!
Strange but true - as said above, the blame will generally be with the driver of the moving vehicle but as with most things in insurance there is no hard and fast rule.
Cheers,
Andy