You refer to the 1917 accusation by Lord Alfred Douglas (1870-1945), poet son of the 9th Marquess of Queensberry and sometime friend of Oscar Wilde, that Churchill had profited by £40,000 by manipulating the press with false communiques after the Battle of Jutland (1916).
Douglas, a flagrant anti-Semite, claimed that Churchill, in the pay of his Jewish banker friend Sir Ernest Cassel, arranged for the government to announce a naval defeat at Jutland (which it did), after which British stocks collapsed in New York (which they did). Churchill then allegedly issued a statement (which he did) saying it wasn’t such a defeat after all (he was asked to do this by the government to boost public morale). The stocks rebounded and Cassel and his friends, who had allegedly bought low, allegedly sold high. To bolster his case, Douglas pointed to Churchill’s bachelor flat at 12 Bolton Street, where Cassel had provided the furniture when Churchill had moved there in 1905.
In 1923 on Churchill’s behalf the Crown filed a criminal libel action against Douglas. Churchill testified, denying the accusations ,or any contact with Cassel or his friends concerning the Battle of Jutland. Douglas was found guilty and sentenced to six months in prison.
A happy postscript: in 1940, Lord Alfred Douglas sent Churchill a poem of praise and hope for his war leadership, which Churchill accepted with his typical magnanimity.
More details are in Martin Gilbert’s Winston S. Churchill, biographic Volume V (available from Hillsdale College Press), his 1994 book In Search of Churchill,and Lord Alfred Douglas’ Wikipedia entry.