Here we have a 5" GWR 15XX pannier tank, to the well respected and powerful little 'Speedy' design by Martin Evans. Well on the way and with a sound, silver soldered copper boiler, this looks to be a model that has either been completely stripped down and rebuilt, including this new boiler, or perhaps it could be an older build that has never quite made it all the way to the steaming stage, it's difficult to tell for sure. But certainly the boiler is brand new and un-fired, and the bottom end machining is neat and solidly made without much slack and slop in it. It looks to us like it ought to work without much difficulty, and to all intense and purposes this one is nearly there!
A little winter project, and bit of a strip down, tidy, ppaint and re-assembly with the final bits and bobs addressed during the re-build and you'll have yourself a finished loco in no time.