Thanks very much guys
The temperature is a comparatively tropical -1 today, I might man-up and get out there to start work on preparing the underside.
What triggered all this was I had a brake line burst on me

As addo says, replacing the flexi hose in situ was very difficult, and the nut rounded off. As dropping the axle was easy, I originally did that to improve access, but one thing led to another and I've ended up rebuilding the whole damn thing. I can't help myself

Interestingly there is no brake balance valve fitted to this car, which is a good thing, as no doubt it would be another item needing attention.
A concours-winning '96 405 diesel Quasar special edition....keep that to yourself Jim, otherwise I might have throngs of classic car collectors breaking down my door!