Exciting news indeed
I agree that the name of the song might reference to Beryl Bryden. In 1997, Mark wrote a foreword together with George Harrison to a book called Skiffle. Skiffle is, according to Wikipedia,
a type of popular music with jazz, blues, folk, and roots influences, usually using homemade or improvised instruments. Originating as a term in the United States in the first half of the twentieth century, it became popular again in the UK in the 1950s, where it was mainly associated with musician Lonnie Donegan and played a major part in beginning the careers of later eminent jazz, pop, blues, folk and rock musicians.This book talks apparantly about Beryl Bryden and Lonni Donegan, amongst others, and it seems that Beryl was a "master" with the washboard
There did at some point exist a group called The Lonnie Donegan Skiffle Group, where Lonnie had guitar and vocals, Chris Barber played double bass, and Beryl Bryden played the washboard. In the video below, form the TV documentary
Lonnie Donegan - This Is Your Life from 1991, you can see the group reunite and play a song from about 8:00 and out
https://www.youtube.com/watch?feature=player_detailpage&v=9vFx-61PeR8So, I suppose Beryl Bryden is the one "Beryl". Or maybe not? Who knows
I wonder if it's a skiffle song, anyway