I did read the discussion above - and would like to add a query to it:

Trevor's discography includes a song "Dorset is beautiful" (recorded by, among others, the Wurzels, The Yetties"

Is that the same song discussed here - a variation of it - or something different that Trevor wrote with the same title?

Certainly, rightly or wrongly, Trevor is 'credited'as the writer of a song called 'Dorset is beautiful' on many sources, for example:
Scrumpt and Western - archive

My memory of what Trevor said about the provenance of the version Trevor sang (and recorded) is imperfect - and sadly, he's not here either to ask...

However, his young son is, and goes off to Dorset next week (his first foray into darkest England from Malawi). It would be great if we can give him an explanation of which song is which; if there are different versions; and the significance, or link, to 'Dorset' and his Dad?