There is a book of condolences on his website, as shown in the link above in danensis's posting.
From what I have heard too it sounds like it was a massive stroke that sadly took him away. He had been due to do another tour in Scotland in March.
He did at one time have a young fiddler in the band called JOE Wright, who came from Norfolk (not too far from Lowestoft, so maybe that's who Captain Birdseye is thinking of?) This was the source of a number of jokes; "the son I never knew I had" at his gigs.
I believe John was from the North of England?