"George Booth" wrote
From 'The English Climate' by H.H. Lamb

'Among the foothills of the Chiltern Hills between Rickmansworth and
Chorleywood, Herts, is a residential district in a little valley 177 feet
above sea level, with the surrounding hills a hundred feet higher. This is
our best studied frost hollow.

This, plus the location given as "Valley Road" have enabled me to make a
better guess of the location.

http://tinyurl.com/5nr7n

(hope that link works!)

However, now that the area is so heavily built up, I would expect that the
frost hollow is very much a thing of the past and there will be much colder
places elsewhere in the local area (eg my original suggstion of Chorleywood
Common)

Jack