Ok, the reason I need a new set of Caliper bolts.
1/ Went into garage today, task, remove front wheel and clean and tidy everything up, same caliper bolts as in original pics.
2/ 3 caliper bolts came undone no issue, but did seem a little tight, (I always copperslip them and torque to the correct value).
3/ The 4th (right side front/top bolt? did not want to move, checked tightness of allen socket in bolt, all good, tried again and the socket allen key twised in the caliper bolt head and splayed the top of the caliper bolt, so it was not coming out.
4/ Shout , scream, pull what is left of hair out.
5/ Have a cup of tea and calm down a bit.
6/ Get electric drill out and trusty tin or ground split point 5% cobalt drills out.
7. Use an 8.5mm bit (as it fits snug in socket head) and just a quick drill as this gives me a near exact centre point into the base of the head of bolt, start with a 3,5mm bit and slowly drill to just below the head of the caliper bolt, using WD-40 as coolant etc (having taped and clothed the rest of the caliper so no swarf got into the business bits), after about 15 20 mins of gentle bit knackering working my way up to a 10mm bit the head of the caliper bolt came off, phew sorted, now just need to take the caliper off tomorrow and remove the bolt.
8/ There will be no pics of said removel as it was painful and embarrassing enough just to type this up.
I did buy those S/Steel caliper bolts off ebay so probably not the best quality, and I will not be going for that style of head again, so there I have fessed up.