It isn't only Boston Lodge which has a problem producing identical carriages.
Left to my own devices there's every chance my latest Super Barn 117 would turn out rather differently from the previous one, 119.
Fortunately, now that Himself lives just a few miles up the road, it is easy for me to raid the stock boxes and get hold of a previous model to aid my memory.
Although the body sides have been cast from the same moulds there's lots of potential for deviance when it comes to things like the depth of the frame which sticks out of the bottom or the detail of the bits and pieces beneath.
So it's invaluable to have it on hand to refer to and cross-check against, the only challenge is to make sure that it doesn't sustain any accidental damage which is all to easily done around a workbench full of sharp tools, bottles of solvent and a house inhabited by young children and a periodically psychotic cat.....