Ken, thanks and sorry for the late reply, I'd clean forgotten I'd even asked , I'll try your technique, I've got a blow torch but I think the flame is a little fierce, its better suited to hot water pipes and the such, more a needle type flame rather than a broad flame I suspect yours gives, picture added.
Re damage to parts, it was a class 57 roof panel with grills etched out, the thinner bars ofthe grills heated quicker than the surrounding roof panel and they all bowed up, luckily being reasonable soft by that stage they rolled back flat and some tweaking with various impliments made them all straight again, with two more panels to do I'm not keen to repeat my mistake.
Gorgous looking loco, I have a real soft spot for the LMS 4-6-0s, not too keen on the unrebuilt Scots (though unrebuilt Patriots are much better proportioned IMHO), much prefer Staniers rebuilds or Jubilees, I think the deflectors really give them a nice touch !. Funds permitting I hope to aquire one later in the year, Gladiator or David Andrews, both kit ranges seem very well recieved by people.
Kindest
Michael