Harold Sidney Harmsworth, 1st Viscount Rothermere, was a leading British newspaper proprietor who owned Associated Newspapers Ltd. He is best known, like his brother Alfred Harmsworth, later Viscount Northcliffe, for the development of the Daily Mail and the Daily Mirror. Rothermere was a pioneer of popular tabloid journalism, and an enthusiastic proponent of closer links between the UK and Nazi Germany of which he was a prominent British admirer.

The Daily Mirror is a British national daily tabloid newspaper. Founded in 1903, it is owned by parent company Reach plc. From 1985 to 1987, and from 1997 to 2002, the title on its masthead was simply The Mirror. It had an average daily print circulation of 716,923 in December 2016, dropping to 587,803 the following year. Its Sunday sister paper is the Sunday Mirror. Unlike other major British tabloids such as The Sun and the Daily Mail, the Mirror has no separate Scottish edition; this function is performed by the Daily Record and the Sunday Mail, which incorporate certain stories from the Mirror that are of Scottish significance.