Thanks for the advice guys. Actually, the purchase of a model to put the "Puffin" in, is on hold as I have already started another project. I am building a steam powered "St Nectan", with the motive power being a double acting twin cylinder, long stroke engine to a French design, made from bar stock. For the choice of engine - blame Bogs, 'e was the one wot suggested it! The Mountfleet kit is awaiting sufficient funding, prior to being shipped out, as the financial constraints imposed by extreme budgetary constraints around here is crippling and much like Gordon Brown's exchequer ... empty ... yep, grand designs, but just about empty .. still, I'll be up and running long before that wonderful Mr Darling has repaired the hole in Mr. Brown's swag bag I can bet ya. Actually, as the engine is the first part of the project already in hand, there is no rush to get the model kit. This is going to be one long term project.
As for the little "Puffin" I was thinking on the lines of another of Mountfleet's wonderful modelsm ... Clannity, the little Admiralty coaster in civilian colours. At 49" length and 9" beam it should be about right. Sorry guys, I'm just not into open type launches, and when all is said and done, when the model boat is out on the lake, all you can see is the steam from the stack, and the silhouette of the boat as she glides through the water. But then, each to their own is my motto.
Attached, (if they upload) are a picture of the engine in outline, and a photo of progress so far. I am keeping a photographic log, and will do a seperate build post, when I have more stuff under construction.