The controversial discussions were a protracted series of meetings of the British Psychoanalytical Society which took place between October 1942 and February 1944 between the Viennese school and the supporters of Melanie Klein.
In these sessions the differences between classical Freudian analysis and newer Kleinian theory were argued with considerable vehemence.
The Freudian side was principally represented by Anna Freud, who was resistant to the revisions of theory and method proposed by Klein as a result of her work as an analyst of young children.
The Klein Group included Susan Isaacs, Joan Riviere, Paula Heimann, and Roger Money-Kyrle.
The "Middle Group", who tried to apply a moderating force included Ella Freeman Sharpe, James Strachey, Sylvia Payne, Donald Winnicott, William Gillespie, Marjorie Brierley, and later, Michael Balint.