Beer knew that Esterhazy was in London because The Observer's Paris correspondent had made a connection with him; she interviewed him twice, and he confessed to being the culprit: I wrote the bordereau.

She published the interviews in September 1898,[7] reporting his confession and writing a leader column accusing the French military of antisemitism and calling for a retrial for the innocent Dreyfus.

[8] Despite this evidence, Dreyfus was found guilty again in a later trial, but following a public outcry was pardoned into house arrest in 1899, and finally exonerated on 12 July 1906, with his military commission restored and promoted to major.

Although she subsequently recovered, Beer required nursing care for the remainder of her life, spending her final years at Chancellor House in Tunbridge Wells, where she died of the disease in 1927.

In her will she left a generous legacy to her nephew Siegfried Sassoon, enabling him to purchase Heytesbury House in Wiltshire, where he spent the rest of his life.

While Beer's husband Frederick was buried in his father's large mausoleum in Highgate Cemetery in north London, her family intervened to prevent her burial in that bastion of Anglican religion.

However, her grave is now located in the municipal cemetery at Tunbridge Wells, and a marker has been added to her headstone in recognition of her work as a journalist and editor, paid for by The Observer and The Sunday Times.