The rear de dion gaiter had fallen apart, it was completely rotten and the keen followers of this saga will have realised that Don split the original by jacking the car up under the de dion tube. He replaced it with a repro one and it hasn't lasted.
I have managed to find a new old stock one, the rubber is at least as twice as thick as the repro one.
Next job is to take out the de dion tube o replace the gaiter. The tube is a later one and is grease filled rather than oil filled.