Thanks for the update, David. Prior to moving to Wales in 2015 we had lived for 15 years in Boxhill (which, for the benefit of those forumites not familiar with the geography of Surrey, is about two miles from the Surrey town of Dorking). I have to admit that I had no knowledge of either Dorking Folk Club or Surrey Hills Radio. In my defence, I wasn't an accordion player then. I was playing drums with Ewell-based Fitznell's Wind Band, and bought my first accordion just before we moved. But as I'm writing this I'm "listening again" to yesterday's edition of The Surrey Folk Show. I think you will have a new regular listener!
There are some good tunes to be found on the East Surrey Hills Morris Men's website, I notice.
There certainly is a connection between English and Welsh folk tunes - similar melodies crop up, sometimes with similar names, sometimes not, though the history is not always clear. Our Welsh traditional dance group, Tipyn o Bopeth, often performs with local Morris sides, and shares some members with them too.