 Born in Wellington he was educated at St Patrick's College.As a schoolboy, McCarthy recalled meeting VC winner Billy Hardham in 1922; "a very silent, simple man" living in a flat in Kelburn who had played rugby for Wellington 51 times, and who gave him a historic book on rugby.A promising rugby union half-back, he played for the Manawatu B and Bush (Now part of Wairarapa-Bush) teams in the 1930s.