Clearing out a little, I have come across a cache of material from my father's Architecture Course at Sheffield University in the late 1950s. There is also a brochure from the GRP products he was offering around 1983 from one of the original Raleigh Buildings in Nottingham.
Lots of interesting projects - this is one for a "Country House", and I can see the stripped down style of the period, but there are also quarters for a maid. And a lot of illlustrations done in watercolour.
And the scale is - yes - 1 inch to 6 feet. Here are a few pics, which are just auto-colour-balanced. The entry was done in haste so there are a couple of duplicates.