Well if Peter won't mind. Some cosmetic work that needed doing. Whom ever replaced the battery way back when broke the retaining bolt/clamp and the resulting battery slapping around made for a nasty racket, not to mention mess as I presume it got a crack in. Or perhaps it was the battery before that that was cracked hence the sheered retaining bolt.
Started off trying to get the isolator off as the one torx screw rusted so bad the t40 stripped it
Got it off and behold the horror
Wirebrush, sandpaper and a vacuum cleaner it was ready to be rust treated.
Given the weather it was much fun sitting with a haor dryer blowing hot air on the rust treatment to get it dry after a hour. After that I tackled the battery isolator (8k from bmw I will have you know).
When the car is with the good doctor we can speak about possible solutions to get a new clamp setup going.