Many thanks for your comments. Since I started constructing this model I've looked more closely at stone buildings and it's suprising just what variations in shade there are. I do wonder though whether when the eye takes in a building close up it tends to look at parts, not the whole, and the variations, whilst there, aren't so noticeable. Looking at a model the eye takes in the whole building and whilst the variations in shade are authentic, because the eye sees the whole building it may look a little overdone.
The website Mikkel has highlighted has I think every photo ever taken of Westbrook. The one of the station in the snow shows that I haven't got the arrangement of the notice boards quite correct, I had this photo but overlooked it. I've now rectified this adding the small enamel notice at the end of the building. The photo also shows that battens were used as I guessed. The photos show ramshackle sheds tacked on to the end of the building. I've constructed these from Plasticard although the platform facing side does not appear in any photos so have had to make a guess as to the appearance, there must have been a door. I painted the sheds but stupidly used a Humbrol dark brown wash which dries to a gloss finish.
The Golden Valley branch was an attractive line, most trains were mixed with a couple of mismatched four wheeled coaches. The 517's worked the line until the Collett 0-4-2T's came along and after a few new examples were used, 5818 settled down to become the Golden Valley loco. It was always kept in immaculate condition.
Next job is the platform surface and a visit to Screwfix for aluminium oxide paper.