Today marks the 50th anniversary of one of the blackest days in British newspaper history. Though almost entirely forgotten, on 15 September 1964 the popular Labour-supporting Daily Herald newspaper was re-launched as The Sun that we all know and loathe today.

The Herald was founded in 1912 by a group of radicals including union leader Ben Tillett and Labour politician George Lansbury. Fighting to establish its name in an industry with prohibitively high capital costs, money was so tight in the early days that at one point the paper came out in pages of different sizes and shapes after some discarded paper supplies had been found. Between 1914 and 1919 financial troubles forced the paper to temporarily publish as a weekly to survive. Luckily, the paper’s politics were built on firmer ground. According to James Curran, Professor of Communications at Goldsmith’s, the Herald was a “freewheeling vehicle of the left, an important channel for the dissemination of syndicalist and socialist ideas”. It gave strong support to industrial action, the suffragettes and Russian Revolution, while opposing the First World War and its attendant conscription.

Taken over by the Trade Union Congress in 1922, the paper’s rebellious independence was neutered, though it continued to provide an alternative analysis and vision of society to the rest of the Tory-dominated press. In 1933 the Herald became the largest circulation daily newspaper in the Western world, topping two million copies a day, despite the hostility of the political class. However, the paper had an Achilles Heel – its readership was overwhelming working-class, older men with little purchasing power.

Why was this a problem? Ever since the repeal of advertising duty in the 1850s, newspapers had become heavily reliant on advertising revenue, as they still are today. Therefore, the key was to attract readers with money to spend. As Sir Charles Higham, the head of a large advertising agency, noted in 1925, “A very limited circulation, but entirely among the wealthy… may be more valuable than if circulation were quadrupled”. This cold economic reality was a disaster for the labour-orientated Herald. “Our success in circulation was our undoing”, Lansbury, then the Editor, said in 1919. “The more copies we sold, the more money we lost.” Previously, governments had tried to restrict working-class and radical publications by levying newspaper stamp duty and taxes. In contrast, Professor Curran believes the Herald’s problems with advertising highlights how “Market forces succeeded where legal repression had failed in conscripting the press to the social order.” The Guardian’s Readers’ Editor, who recently argued that it was advertising that led to the independence of the press, should take note.

After the Second World War, the Herald’s money problems continued, the paper moving from one crisis to another. These difficulties shouldn’t be confused with unpopularity. In the Herald’s last year of publication it had a circulation of 1.2 million, more than five times the circulation of The Times, and a readership of over 4.7 million – double the readership of The Times, the Financial Times and The Guardian combined. However, even though it achieved 8.1% of national daily circulation, the paper only received 3.5% of net advertising revenue.

In an effort to secure the future of the paper, in the 1950s the Herald’s management turned to market research (which found the paper had the most devoted readership of all newspapers). Informed by the results, the Herald was re-launched as The Sun in an attempt to diversify and ‘upgrade’ the readership – to produce a “more representative make-up essential to advertisers”, as an internal memo put it. Writing in his diary at the time, Tony Benn described the transformed paper as “appalling… basically the same minus the Herald political content.”

Increasingly commercial and politically directionless, the paper staggered on until  1969 when a then little known Australian newspaper owner called Rupert Murdoch bought it and the sexist, celebrity-obsessed, news-lite, Thatcherite Sun was born.

It was a hugely ironic ending for a paper that had been a consistent voice for the working-class and labour movement. Continuously undermined by market forces, Professor Curran notes it had the indignity of being of being “converted into a paper which stood for everything the old Daily Herald had opposed”.

The Herald’s loss is especially noticeable today. The majority of the national press continue to tack to the political right, and is far to the right of the general public on many major issues. Even the Guardian, generally considered the most liberal and left-wing national daily, has shown great hostility to trade unions on occasion.

15 September 1964 was a dark day indeed.

This article was inspired by and largely sourced from James Curran and Jean Seaton’s Power Without Responsibility: The Press, Broadcasting and the New Media in Britain and Huw Richards’s The Bloody Circus:  The Daily Herald and the Left.