Just came across this album of pictures, most of which date from the 1980s, and were taken by a signalman, going by a caption reference, though there's very little caption information and even I had to think hard on the locations of some pictures, such are the differences in vegetation over the years.
http://s997.photobucket.com/albums/af99/wimmer10/British%20Rail%20Cotswold%20Line/Lots of
BR▸ blue diesels, of several varieties, including such rarities as a Peak on one-coach inspection train and a pair of Class 20s.