His father Harold F. Rubinstein (1891–1975) was a solicitor with expertise in publishing matters; he acted on the defence of Radclyffe Hall's novel, The Well of Loneliness on obscenity charges in 1928.
[1] Helge Rubinstein worked as a marriage guidance counsellor, published several cookery books, and founded the Ben's Cookies biscuit chain (named after their youngest son).
He then became a literary agent at the long-established firm A. P. Watt, where he represented many successful clients, including Quentin Blake, Nadine Gordimer, Jan Morris, Geoffrey Moorhouse, P. G. Wodehouse, and the estates of G. K. Chesterton, Robert Graves, Rudyard Kipling, Somerset Maugham, H. G. Wells, and W. B. Yeats.
He also acted as agent for John Colville, private secretary to Winston Churchill, who published his memoirs The Fringes of Power: Downing Street Diaries 1939-1955.
Rubinstein retired from AP Watt in 1992, but continued to work as a literary agent independently, controversially acting for Mary Bell, the 1960s child murderer, whose biography Cries Unheard written with Gitta Sereny was published in 1998.