My name is David Martin and I am from a Jewish family of Martin's. I am also from the UK and my family have been there for a very long time. We were origionaly Saphardic origin and became ashkinazie over time. We were origionaly members of the Beavis Marks synagogue in London which has Sephardic orthodox origins but later became more reform and ashkenazie. My Great Grandmothers family were Moss.
Just saw your blog and thought it was interesting.
I know a number of other Martin's in the UK not related to myself also.