So the MOT fail was slightly high emissions (not a problem on a F according to the MOT tester man) and poor rear brakes (both road and parking).
So today I popped her up and whipped off the N/S/R wheel, attached the wire brush to the angle grinder and proceeded to clean up the disc. I decided that the easy way to do the inside face of the disc was to remove it and, although it cleaned up quite well, I may as well stick on the new discs I already have.
However I found the cause of the knocking AND the real reason for the poor rear brakes.
According to Rimmers blow up diagrams the front mount for the long suspension arm only has a bolt and no nut, the O/S mount obviously needed a nut as the bolt slipped all the way through, and I managed to find a photo showing said bolt.
However the N/S appeared to have a thread and appeared to tighten up. And I couldn't find any evidence to the contrary. However finding the bolt mostly out of it's ole advises that it needs a nut. And was probably the cause of the knocking. And moving around it has crushed the new brake pipes I have fitted.
I managed to lose the brand new bolt but did find a replacement bolt and matching nut (M10 80mm bolt with a 15mm shouldered head and M10 nut with shouldered 19mm head for the interested ones). And fitted same.
I started repairing the damaged brake pipes with a brake pipe flaring tool I've since last century but never used. However learning a new skill as it started to rain wasn't a good idea so I packed the tools away and had a drink instead.
Home to black Alfa Romeo 159 3.2 V6 Q4 ,green MGF VVC and red MG Maestro T16.
MG - the friendly marque.