I don't know if he is related, but if I remember correctly, Alan Tonks left for Leigh before Maurice Bamford's first game in charge - which I believe was the infamous K-9 game at Headingley. Having joined earlier that season, he never actually appeared in a winning Halifax side.
I don't think he stayed at Leigh long, returning back to Yorkshire (Batley?) where his career was brought to a premature end by illness which went on to claim him at a tragically early age.