Born in Portsmouth, Marlowe studied medicine at Queen's College, Galway, and then at the London Hospital.
He left his studies, without graduating, when he was offered the chance to train as a journalist at The Star.
Marlowe occasionally came into conflict with Northcliffe, in particular at the start of World War I when Northcliffe opposed sending British troops overseas, but Marlowe persuaded him to change his mind.
[2] Ahead of the 1924 UK general election, Marlowe published the Zinoviev letter, a fake document purporting to show Soviet interference in British politics.
For the rest of his life, Marlowe claimed that the letter was genuine, and that if he had not published it, the Foreign Office would have kept it secret until after the election.