The switch mech turned out to be easily sorted with snipe nose pliers and patience, then I started on the horn pickup.
A bit of lateral thinking, and an old domestic ceiling lampholder did the job. If you dismantle one of these ordinary bayonet fitments, you will find the cylindrical brass contacts which push on the bottom of the bulb. These are internally spring loaded and fit a treat in the position shown below, soldered to the flat part of the old wiper. Lovely smooth pickup action now, should take a while to wear through that bugger!! (photo taken before trimming the old bent up wiper bit off)<br>
Oh and as a grand finale, never having had a thin wall socket for the steering wheel nut, I found an old nut 1 3/16" across flats which had some kind of metric thread which happened to be bigger than the moggy column thread, positioned it carefully on top of the moggy nut, and tag welded it on. Now I can tighten the steering wheel with something more than long nosed pliers!! Some people say I should have been born a Scot!