Here’s the 1954 book Come out with me, Lewis Wilshire’s 1954 attempt to get townies out into the countryside. Clive Pratt wrote about this below; here’s pp3–31 with the reference he asked about:

It’s a delightful description of walking up the Roundhill. He appreciates the view, and writes about wildflowers that I’m not certain we see today.

The one bit we take issue with is where he says “it was here on Kelston Round-hill that Sir John Harington built a castle” etc. The castle (or rather, manor-house) was at the foot of the Roundhill, in the village of Kelston where you can still see its outline today.

Anyway thanks Clive for the enquiry and for sending in the scans.