Enjoying (?) a monday off, so far removed nsf caliper and replaced with the spare that was in the garage, which is also fecking well seized (argh!)
On the plus front after spending ages pratting about with the starter motor wiring, spotted the tiniest nick out of one of the 2 wires midaway between the 2 terminals I was convinced was causing the problem, so billy bonus simple fix sorted for that one, just wish I'd thought of checking the most obvious simple thing first, ho hum!