Good day, bad day.
Good day because having cut the washer pipe after the pump and fitted the inline non return valve I now have windscreen washers again. A simple fix, maybe the bellows are on their way out but fine for now. I've saved the details of the electric kit options just in case.
Bad day because I discovered the horns are fried. Remplacemnt ordered.
To finish off the wash / wipe system I need to 'tweak' the wiper movement as they refuse to do a full sweep. Motor sounds ok so I will start with a general 'look see' inside the unit - I am sure I have notes somewhere about adjusting the park settings. Strangely my system seems to be a LHD set up, i.e. blades park over on the passenger side.
Don't really need wipers though as it never rains in Normandy, the MOT man might want to try them out at the next visit. I'm positive he didn't do it last time as he didn't come and ask me how the wipers & washers operated
Thanks to everyone for the input, all very useful