The temp sensor checked out ok (reads between 2.1 to 2.9K ohms) so i moved onto the plugs. The spark seemed poor and I wasn't (at one point at least) getting a spark on one plug. As the plugs were fairly new i banked on the coils. This made no difference at the time but i think this was more to do with a crack in a fuel hose between the filter and pump. I suspect the pump was pulling in air with the fuel which was killing the mix.
Unfortunately for me the fuel hose with the leak is a part that takes the 12mm presented by the pump down to 8mm on the filter - part 22 in this diagram. This part doesn't seem to be available anywhere so i ended up using a converter adapter and a very short piece of 12mm hose.
After reading a few posts about the spark plugs that contain an arresting resistor I decided to also replace the plugs. Basically the plugs with the resistor (BR8ES) suppress noise from the ignition to help with stability of any on board computer systems. The down side is a weaker spark (apparently) so I have fitted standard B8ES NKG plus.
Its early days but at least she now starts and idles ok. A long ride is now in order this weekend ..