As a BBC announcer, McCullock was commentator on the first radio broadcast of an FA Cup Final in 1927. He helped to set up Children's Hour in 1933 and took over as its director a few years later. Known to children as 'Uncle Mac', his closing catchphrase, “Goodnight Children; Everywhere” was eagerly anticipated by listeners. McCulloch was an acomplished radio actor and provided the voice of Larry the Lamb in the children's series, Toytown. He left the BBC due to ill-health, but returned to host a record request show Children's Favourites for a further 10 years.