Congratulations Karen Bradley! The secretary of state for culture, media and sport has become the first Conservative in office since John Major to stand up to Rupert Murdoch in his quest to expand his global media empire. Mrs Bradley had been considering the bid by 21st Century Fox, effectively controlled by the Murdoch family, to buy the remaining 61% of Sky, the pan-European broadcaster and internet services provider, that it does not already own. She had been minded to refer the bid on the grounds of media plurality to the competition watchdog – the Competition and Markets Authority (CMA) – on the advice of the broadcasting regulator Ofcom, the prospect of which would hardly cause Mr Murdoch much lost sleep, since his companies relish scrapping with dominant web giants like Google. When it came to broadcasting standards, Ofcom dismissed concerns over the Murdochs’ commitment to the taste and truthfulness of his companies’ output. Yet the culture secretary disagreed, saying “non-fanciful concerns” about the Murdochs’ commitment to standards meant she would have to refer the deal to the competition regulator on these grounds, too.

This opens up a new front against Mr Murdoch, who has expressed a wish to make Sky News – an impartial broadcaster – more like Fox News, a highly partisan rightwing US outlet accused of peddling conspiracy theories and fake news. The “Foxification” of Murdoch’s UK news station is something, the culture secretary correctly points out, that should be investigated. What is remarkable is that Mrs Bradley has done the right thing by looking at the questions of character, culture and criminality that the rest of the world fixates on when dealing with the Murdochs. Ofcom, on the other hand, has questions to answer about its apparent naivety in dealing with the takeover. When Ofcom discovered that Fox News had no code of compliance despite broadcasting in this country, it allowed Fox to produce one and abide by it. Just a day after Fox News put in a place its code, it ran a false story, politically significant in the US, besmirching the reputation of a murdered Democratic National Committee official, saying he had been a traitor. The story was retracted a week later, but four months on, no action has been taken against those responsible. There has been no apology to the dead man’s family, who publicly explained that claims of treason had added to their grief. In August Fox News, acting CEO Rupert Murdoch, was taken off air in Britain. If actions can be interpreted as an admission of wrongdoing, then Fox News is guilty. But so is Ofcom. The regulator failed first to police Fox News and then to recognise that the legal threshold for referring the bid on grounds of broadcasting standards was low, and easily met in the case of the Murdochs. That was a mistake by Ofcom – and one the culture secretary could not repeat.

This is not the end of the matter, it is the end of the beginning. The CMA must reassure the public that it will act without fear or favour, and prove it is capable of running a high-profile, complex and politically sensitive inquiry. The scope of the investigation must include how the Murdochs seek to influence politics. In the US there is evidence that Fox News provides effective propaganda for rightwing Republicans. In this country peers have raised concerns that the TV viewing, internet and phone records of 13m households could be misused for political purposes were the Murdochs to own 100% of Sky. While impartiality laws govern broadcasters, net neutrality rules, in force in the UK as a result of EU law, prevent the misuse of gatekeeper powers over the internet. These might disappear after Brexit.

Above all, the CMA will need to gauge the Murdochs’ commitment to standards. There must be an emphasis on whether it is right to concentrate so much media power in the hands of the Murdochs, with their companies’ history of disturbing corporate behaviour and lawbreaking.