Half brother put up for adoption.

Hi, I am 34 and found out a few years ago that I have a brother who was put up for adoption. I only found out from my other brother who told me our mother who drinks blurted it out one night - she has no memory of telling him. My father and Aunt have confirmed this to be true but no one will give me the right information. I am told he is a few years older than me, about three or four years older. The adoption took place in Leicestershire UK and that he lives in New Zealand. My mothers maiden name is Martin, she was married to someone before my dad but I am told he is not his son but my mother may have used this as a surname which would be Frith. I really would like to find him.