What I meant, lightengine, was that Allan's walls look a lot thicker and more robust, indeed more like a castle than mine! His are 8mm thick if I read the description of his sandwich correctly whereas mine are plain vanilla Scalescenes so on a combination of 1.5mm & 2mm mountboard and in places bits of corrugated cardboard to secure them to the side of the layout box.
In terms of day-to-day use on my railway mine work fine, though as they are fixed to the afore mentioned layout box. The layout folds up into the wall, hence having the box round it. Perhaps this picture will help:
The wall is firmly glued down at the bottom with Evostick (and later held in place with PVA and ballast); you can then see a strip of corrugated card glued to the back of the wall & in turn to the woodwork at the top of the main part of the wall level with the top of the buttresses, again using Evostick; and then the very top edge of the parapet is similarly glued in place. It's all pretty tough and I eventually dispensed with the supports behind the wall su[pplied with the kit as I couldn't be bothered to cut out all the triangles!