Thanks everyone, some great info there. Mine is an S but I thought the ride height change was done by the springs so maybe the 5mm is something else. The previous owner might have changed a strut when he crashed it but I doubt he would have got mk2 or 3 as not many around over here 20 years ago. Or maybe is a factory thing to compensate for road camber, driver weight? Maybe just a factory tolerance.
No oil came out (shouldnt be any in there?), and they are straight, but each strut has a metal collar in it, about 2 inches in on one and 4 inches on the other. No idea what they are for but am thinking they are rusted in.
I've made a jig so just have to get my porta pack working to see if I can pull them out - big hammer didn't work.