The new prop shaft arrived yesterday and it looks very professionally done. It has the Ford Transit engine UJ on the front and the Morris UJ on the back now so I have removed the adaptor plate from the gearbox. The prop shaft guy said this might have been the source of the problem as it didn't have a centering pin and could have allowed shaking.
I have just returned from Clerkenwell Screws and Nuts where I bought some fresh nuts and bolts and tonight I will screw it all together, in the dark, wet greasy road. Hopefully the next post will be about how good it felt to drive Althea again. But regulars to this blog will not be holding their breath.