I had a crack at painting one of the character pegs and there was a bit of a weird reaction when I lacquered the finished, painted piece.
I washed the figure, under-coated it using a Halford's rattle can primer, then used GW Citadel paints and spray varnish; the plastic softened noticeably after the varnish and the paint lifted. Luckily I was able to scrub it all off with only minor discolouration/scuffing of the peg.
My advice would be to experiment with your primer/paint/varnish combo on the removable section of Thunderbird 2 before risking the rest of the plastic bits...
Yikes - sorry to hear that but thanks for the advice.