Having almost destroyed the caliper piston trying to remove it by heating the caliper in the kitchen workshop oven and then hitting it with a hammer my fucking patience blew.
I even took it to kempton bike jumble with me, stick the caliper in a lathe was one opinion (big chuck!), my mate Paul suggested heating just the piston or freezing just the piston...
This morning I 'googled' it and voila, theres the airline option (seemed a bit dangerous and I don't have an airline) and this the 'grease gun option'
I found my old gun and a flexible connection which made it a lot easier and screwed into the banjo bolt hole.
And fuck me it worked