Salisbury, Napoleon, Churchill: Andrew Roberts has an excellent eye for ‘great men’ who were not merely great but also colourful and helped shape their eras. His latest subject certainly helped shape his era, but he was not a ruler. Alfred Harmsworth, Lord Northcliffe, was a press baron – Britain’s greatest, as Roberts accurately says.

Northcliffe was, like Roberts’s other subjects, born at a fortunate time. He lived through the heyday of the popular press. The 1870 Education Act brought into being board schools; the arrival of compulsory education came a decade later. By the end of the century, most working people could read. Printing technology had become faster and cheaper; railways crisscrossed the country, overnight trains sorting and distributing the national press. The arrival of the telephone and the camera added speed and spice to reporting. The period from 1890 to 1910 saw an unprecedented and unsurpassed boom in the circulation of newspapers and journals.

There were some great stories to report. There was Joseph Chamberlain’s campaign for imperial preference and an end to half a century of free trade. There was the Boer War. There was the arrival of new technologies: cars, aeroplanes, typewriters and ticker tape. Women were acquiring, if not the right to vote, then literacy, jobs and salaries of their own. Above all, there were the gathering clouds and then the misery of the First World War. As the most powerful newspaper baron in the world, Northcliffe was both a spectator of and, as time went on, a player in all this.

Born in a suburb of Dublin to a father who was ‘a dedicated but apologetic drunk’ and a mother who was a formidable Ulsterwoman, the young Alfred Harmsworth was the eldest child in a family that ultimately comprised eleven children. He adored his mother, Geraldine, and wrote to