Problem located.
its the Sundial Y Diverter.
I took the cover off and had a poke about with the actual mechanism and it appears like it has stuck. with a screwdriver placed on the actual mechanism i am able to give it a little flick and the biler and pump fire up.
Is it possible to change parts or am i looking at a new diverter? ref is Honeywell V4073A
based on your info mate I wouldn't replace that yet,its more likely to be the programmer, its easy to check even without a multimeter,I'd check to see if the programmer clock is working ie does it keep time?
Matt