Yet he desired to return to the world of journalism, and in 1900 eagerly accepted Alfred Harmsworth's offer of a position as news editor of the Daily Mail.

Blumenfeld remained editor of the paper until 1929, but he gradually found himself marginalized as Beaverbrook (as Aitken was subsequently ennobled) assumed an intrusive role in editorial matters.

[3]: 330 Politically Blumenfeld was a strong supporter of laissez-faire economics and a harsh critic of socialism and to this end he established the Anti-Socialist Union in 1908 and succeeded in linking the group closely to the Conservative Party.

[7]: 319 After turning over editorship of the paper to his protégé Beverley Baxter, Blumenfeld wrote a number of books, including What is a Journalist (1930) and The Press in My Time (1932).

In 1935, after broadcasting a series of talks on BBC Radio called "Anywhere for a News Story", Blumenfeld retired to Muscombs, a farmhouse in Great Dunmow, Essex.