Well it has been sorted by buying a new switch.
I started to fit the new unit when Tom arrived and took over the installation of the new switch this did include forgetting to put on of the outer casings on first and other little mishaps that probably wouldn't have happened it tom was left on his own.
We knew it worked as we tested it first but after refitting everthing the bike was a dead as a Dodo.
It transpired after seeing smoke from near the battery terminal that the screws had worked loose. This may have been the reason my satnag kept turning off and the bike stuttered a bit when starting, a bit like the hot start problem. Anyway after tightening the screws all was OK. The battery is a Motobatt with universal type terminals with a U shaped adaptor that screws into the battery and the bike lead connects to the top on the U adaptor with the potential of four screws working loose, and they did.
So problem has been solved, just need to check the battery terminals more often. The question posed was are loose terminals related to the hot start problems.
I'm sure Tom will be along to clarify everything