Welcome Huw,

With a name like Lillywhite the banjo link was obvious!!

Derek Lillywhite was around the banjo scene when I was taking Classic Banjo lessons from Chris Sands and I met your Dad in London and at Wythenshaw Forum in Manchester (I believe) where he was judging at a banjo festival around 1980.

here is a link: 

http://classic-banjo.ning.com/forum/topics/derek-lillywhite

I hope that your Dad is still around and playing the banjo!