Yea I've read that thread probably 4 times now , I could go with that but having looked through the bikes on Classic Lightweights (thanks a million to Clydesdale Scot for the tip on how to search that site) I reckon it will look a lot better to have the trigger next to the brake lever. Given it would have the same indexing points as the DT shifter you would hope it will work.
Thanks for that Richard, I still have the Sturmey that came with the bike which is a December 64 dated AW, it looks to be in pretty good nick. I've never worked on a Sturmey before and the tiny little threaded section frightened me off but after looking at Sheldon's article it sounds almost as simple as the Nexus. Time to compare the gearing possibilities .