There was one reason for the recommendation that Rupert Murdoch’s bid for Sky should be blocked: the media empire he runs in the UK simply has too much power and influence. It is refreshing to hear a regulator acknowledge that fact in admirably straightforward language. The Competition and Markets Authority’s (CMA) ruling is a victory for campaigners who have highlighted the influence Murdoch has wielded over successive governments and prime ministers.

It now falls to the culture secretary, Matt Hancock, to show that era is finally drawing to a close by accepting the authority’s decision and blocking Fox’s bid to acquire the 61% of Sky it doesn’t already own. Technically, he can ignore its ruling. Politically, it would be foolish to do so. Perhaps most tellingly of all, the risk attached to blocking the bid is far smaller than it once would have been.

The last general election showed that the power of Murdoch’s papers, and the Sun in particular, is waning. Its coverage of the Labour party was arguably the most biased since the 1992 election, when the paper infamously claimed it had prevented Neil Kinnock entering Downing Street. Even if it was The Sun Wot Won It – and many think it wasn’t – it is a claim the paper could never make now.

Theresa May still refuses to publish a full account of her secret meeting with Murdoch in New York in 2016. The CMA has been braver and bolder than the prime minister by making it clear that it’s unhealthy for a single person or company to control such a huge swath of the UK news industry.

Rupert Murdoch’s hegemony corroded our political system and bent it out of shape

Murdoch’s hegemony corroded our political system and bent it out of shape. In the past, rules that applied to his competitors were not applied to him. News Corporation used its dominant position in the newspaper market to lobby successfully for legislation to be changed so Sky had the right to buy Channel 5, had it chosen to do so. Murdoch’s personal relationship with Margaret Thatcher meant he received the assurances he needed from her to move his newspapers to Wapping. Competitors who had a right to expect a level playing field found that Murdoch’s power had tilted it in his favour.

Those who felt Murdoch had become untouchable had good reason to do so. It was in this context that a corporate culture emerged in which executives were able to collude in and then cover up criminality at his newspapers. The Sun is still fighting civil cases brought by victims of phone-hacking in the UK and the scandal had a sequel in the US, where senior figures at Fox News were involved in payoffs in order to conceal allegations of sexual harassment. Late last year I met a group of Fox News journalists who have been treated appallingly by the company. That’s one reason I don’t agree with the CMA’s finding that Fox hasn’t breached broadcasting standards – and neither will they.

The phone-hacking affair forced Murdoch to abandon his last attempt to take control of Sky in 2011. But is worth remembering that Jeremy Hunt, who was culture secretary at the time, had already cleared it after Sky promised to spin off Sky News.

This time round the company threatened to close it if the deal was blocked, a move that would have resulted in thousands of job losses. Journalists and production staff would have paid a heavy price for the company’s petulance had the threat been carried out. That is now unlikely to happen because Fox’s entertainment assets – including Sky – are being sold off to the much larger Disney, which is hardly the fairytale ending the Murdoch had envisaged.

If the bid is indeed blocked, it will be the first example of May standing up to the rich and powerful since she first promised to do so on the steps of Downing Street 18 months ago. She probably wasn’t thinking of Murdoch when she said it, but events have a way of overtaking this prime minister. Now they are overtaking the Murdochs too.

• Tom Watson is Labour MP for West Bromwich East and deputy leader of the Labour party