From what I've heard it was more than 2 fold - One additional problem comes from using porous castings. The castings were impregnated after machining to stop leakage but impregnation is not the most robust process in the world, and a porous base material with a skin on it is not the same as a non porous casting.This problem was two-fold. 1. From factory, plastic dowels were used to locate the head and if you get severe overheating problems these dowels fail. The new gasket kits have steel dowels which solve the problem.
2. Rover used a really tiny capacity water system, so when there was a leak it does not take long for the car to boil up and so coupled with the plastic dowels you have a knackered head gasket.
The K-series range was expanded in a hurry when they had to stop using Honda engines and some of the original handling equipment and tooling was 'overworked' as the acountants didn't allow enough investment for the expanded range. Any machining imperfections and inherent porosity can add to the problems.
This is of course just what I've heard (from ex-Rover design guys)
The problems became more widespread after the range was increased but as mentioned already - the improved gaskets are a big help.
The difference between a K series headgasket failure and any other car is that people are in a rush to dwell on any problem with Rover parts.
My mum's Fiat Punto head failed after less than 5 years, and apparently this is quite common, but as it's not British I've not heard much about the problems.
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