Thank you from the input - much appreciated.
The article was very useful and I think it resembles the MO of pseudomonas quite closely. The pics on Michael's blog do resemble many of the branches on my tree, especially the the white raised mottling around the purply black dead patches.
MACH - I love your maples btw - always look forward to your threads / progressions!
OK plan of action then - if you guys want to add to it or suggest other preventative measures I am all ears. I'm just writing it so I am clear in my head the way to go:
1. Move the plant into a cold garage and keep it on the dry side over Winter. This disease flourishes in the damp cool months of Winter.
2. Totally clear the soil of debris and bin it.
3.Completely drench the plant (stems / soil) with copper sulphate to eliminate an spores on the bark or soil surface.
3. Mix up a sterilising solution - 1 part water to 3 parts bleach. Branch cutters will be left in the solution 5 mins between every cut. Cut out the infected tissue and bin it.
4. Same as 3 after each cut so that the cut area gets a drench of copper sulphate too. Seal all cuts with vaseline.
5. Treat at monthly intervals with follow up spraying
6. Pray
EDIT: Just an interesting fact: Pseudomonas has a necrotising effect on bark due to lowering it's anti freeze properties, making die back as a result of cold weather conditions more likely.