Well, I checked out the Wellington Hotel and it didn't match
But.........I took the names of the towns you listed and started looking at the pubs that are listed as in or near St Tudy annnnnnnnnnnnddddddddd I found it!
I suspectedcit was the St Mabyn Inn. I only found a couple of pictures online and was about 75% sure I had it when all of a sudden I found a page of pictures from 1968. There was one with the stairway in the background! Then I found a site that has the pub for sale and two of the pictures clinched it - one even had the Gold Flake poster in the right place.
It IS the St Mabyn Inn. Since the pub is currently for sale I wonder if they will rent it out for use again this spring?
Thanks so much Adelie! Your work put me on the right track. Now if I could find that frickken hotel interior!