Just to go back to PNs post at #7, examples of these strange shaped roofs can be seen here:
Flickr: 814man's Photostream
which are a series of images I took during a survey of old nuclear storage sites in 2001. There are existing examples shown from Honington, Marham, Waddington and Wittering. There were no such buildings constructed at Scampton, whilst due to its current use I was unable to take pictures of the ones at Faldingworth, although I can confirm there was actually the largest concentration of them at over 20, most other sites having only 2 or 3. At Barnham for some reason all the same use buildings had normal square shaped roofs as can be seen.
My understanding was that although those looking would have a pretty good idea of the use of the site, due to what was stored in these specific buildings their number would provide a good indication of the number of weapons stored at the site.