Y'all ready for this?.......
So on the way home from work tonight I had a moment of lucidity. Thought wait. Surely if I am pulling the washer stalk towards me and the windscreen wipers are not firing (they are working every other way but just not when I try to get the washers to skoosh) that there is a chance that the fault might be the stalk.....
So musing over this a bit I decide to give the top of the steering column a firm but gentle thwack....sure enough one hit and the windscreen washers come to life after a week of being inop!,,
Clearly a dodgy microswitch with some gunk in it or something....either way it's now working!
Should I investigate further and track down the switch and skoosh in some wd40?
Else I will just leave it and get it looked at in the next service