As I can't update the question ...
I found a help manual on the web. It recommended removing the filter and seeing if the primer worked - it didn't. So I added a teaspoon of fuel into the carb and voila it fired up but quickly died again (1 - 3 seconds). Looks like a potential diaphram problem (unless anyone can advise differently).
Link to help I found - http://www.mowerfix.info/OperatingManuals.htm (self help guides and manuals)
Ray
July 2010