Parliament will tomorrow agree new measures to protect the identities of those who, with good reason, give sensitive information to journalists: whistleblowers. This victory for press freedom follows the discovery that police were helping themselves to the phone records of reporters and so were easily able to tell who their sources were. In future a judge will have to be convinced that such access is justified.

As a relatively new observer of the politics of the press, what I find most remarkable about this victory is who sorted it out, because it tells you a lot about who really cares for freedom of expression in this country. (A clue: not the people who make most noise about it.)

Three groups made the difference: working journalists, marshalled by the trade magazine, Press Gazette; some politicians, particularly Lib Dems, who were quick to see something had to be done; and third, Hacked Off, on whose board I sit. Hacked Off researched the issue, took specialist advice, drafted amendments in both houses, briefed MPs and peers, and did its utmost to ensure change would actually happen.

Conspicuously absent from this line-up are the editors and proprietors of our biggest national newspaper companies. Or their usually very busy lawyers. Absent too are Conservative ministers; they tried to protect the status quo. On the face of it these absences should be a surprise, because the public posturing of the big newspaper bosses and their friends in the Tory leadership is all about press freedom.

Rupert Murdoch, Paul Dacre and Lord Guy Black (executive director of the Telegraph Group) were only too eager to raise the false flag of press freedom when the Leveson inquiry was probing their industry’s law-breaking and its shamefully low ethical standards. And David Cameron grabbed a corner of the same flag when he called for the Leveson recommendations to be watered down.

They talk the talk, but when it comes to upholding the freedom of journalists to conduct investigations in the public interest, they do not walk the walk.

It’s true that some editors published indignant leading articles on the subject, but most preferred victimhood to change. They wanted the world to think this was just part of an ancient pattern of oppression of the press by politicians, when in truth the original loophole in the legal protections resulted from an oversight, and there was more than enough political will to plug it.

If it had been left to them, the loophole would still exist.

At the same time they called for more snooping by the police and GCHQ on everyone else, and continued to hide the facts of illegal newspaper snooping on ordinary citizens.

Their behaviour is no surprise to those of us who have followed events since the Leveson report in 2012. First the big companies rejected a British equivalent of the US first amendment, designed to uphold press freedom. (The Guardian could have done with that when the spooks came calling for the Snowden files.) Next they rejected unprecedented protection against the scourge that is “chilling” – the gagging of journalists by threats of expensive legal action. And then they turned up their noses at the idea that their own journalists should have whistleblowers’ rights.

Now the Telegraph’s former chief political commentator, Peter Oborne, informs us (in the teeth of the most unconvincing denials) that his paper’s bosses refused to publish articles that might offend a big advertiser. That’s not a free press; it’s journalism for a price.

Again it’s no surprise that the Telegraph executive named and blamed by Oborne is Murdoch MacLennan, one of the puppeteers of Ipso, the Independent Press Standards Organisation: the sham self-regulator set up by the big press companies. Such people are not pillars of press freedom. They are its enemies, just as they are the enemies of the ordinary people that their papers abuse and exploit in pursuit of “news”, by which both they and I mean sales and sensation.

Where is the Guardian in all this? Much to its credit, it is already a pariah in such company, having exposed phone-hacking and offended against the authoritarian instincts of the big proprietors by revealing what our security services get up to.

The Guardian will probably benefit most from tomorrow’s closing of the loophole because it is by far our most active investigative paper. That is good news, but it makes it all the more frustrating that the Guardian will not take a step that would enhance press freedom much more. It is a step that could also be decisive in raising ethical standards across the industry and protecting ordinary people from unjustified cruelty. That step is to embrace the system recommended by Sir Brian Leveson.

He cherished the freedom of the press, and his recommendations not only painstakingly shield news publishers from political meddling but also offer fresh protections for investigative reporters. Yes, there is a chorus of people saying the contrary, but look who’s leading it: the MacLennans, Murdochs and Dacres. They care nothing for press freedom, or the truth.

So the Guardian, with all the moral authority it has gained from its recent investigative triumphs, can do something important to advance the cause of press freedom, by signing up to Leveson. And if it is hesitating, perhaps it should ask for the advice of its readers.