"I sent you very recently Unwin's letter to BR returning the memorandum", i.e. the private memorandum written by BR "on the failure of his early marriage and his relationships with various women". "Jack Black would like any evidence that there is to establish the date of the memorandum, as it is undated...."

There are various forms of BR's letter to Unwin in the Russell Archives. See record 120777, record 50907, record 14742, and record 123119.