http://www.ebay.co.uk/itm/Live-Steam-Locomotive-Great-Northern-Railway-Pegasus-class-/192197908959?hash=item2cbfe359df:g:Q98AAOSwfRdZJ~oE
The vendor knows nothing about it and the photos don't show what you want to see, but he knows it is Gauge 3.
In my inexpert opinion this is made from castings and is probably Carson. As such it is rare - much rarer than the Carson Experiment. Even so, half the asking price might be more reasonable.
Mike
Perhaps I should correct that. I think the main body parts are cast and probably Carson. The tender is not and who knows about the mechanical bits we can't see.