Complex sentence: Smart became widely known outside the Academy, at least in Britain, when he was editorial consultant for the major BBC television series, The Long Search (1977) while his "The World's Religions" (1989) also reached a considerable popular readership.
Split into simpler sentences: Smart became widely known outside the Academy, at least in Britain, when he was editorial consultant for the major BBC television series, The Long Search (1977). His book "The World's Religions" (1989) also reached a considerable popular readership.