The first time I came across Jonathan Portes, he nitpicked me.

I’d just published a piece on the New Statesman politics blog, the Staggers, about the idea of a universal basic income, with the (I thought) enticing headline: “What would you do with an extra £71 per week?”

Then Portes popped up to remind us that the policy is actually cost-neutral, so no, you wouldn’t directly receive that extra money each week. "Terrible strapline," he tweeted on August 18. "Scheme is revenue neutral - average person would have 'extra £zero per week'."

He then had a longer discussion over Twitter with the author of the article, arguing his case, but it didn’t develop into a complaint or a post on his blog elaborating on the subject. It was a low-level Portes-ing.

Others have not escaped so easily. In the last few years, Portes – the director of the National Institute of Economic and Social Research, formerly chief economist at the Cabinet Office under Gordon Brown – has developed into a role you might call the People's Pedant. He is tirelessly vigilant on Twitter, and escalates particularly egregious cases with a complaint to the Press Complaints Commission – now the Independent Press Standards Organisation, or Ipso.

He calls it “factchecking the UK press”, and tells me he’s made “between 12 and 15” such complaints so far.

His most recent triumph was a landmark decision by Ipso to force The Times to print a frontpage correction, following a splash it ran shortly before the election: "Labour's £1,000 tax on families".

Portes complained about the piece’s inaccurate use of statistics. The headline and opening sentence of the story claimed that Labour, were it to win the election, would saddle "every working family" with extra taxes worth £1,000. Portes' correction, accepted by the paper, pointed out that Labour would primarily raise its proposed taxes from companies and the richest individuals – so they would not affect all families equally.

He also found the story’s calculation misleading, as the ONS data upon which it was based was about “working households” only (a statistical term for households in which every working-age individual is in work), not all families where at least one adult was in work.

Portes eventually succeeded in having the correction published with the prominence he believed it deserved.

“One of the new features of Ipso is that it has this power to require prominence,” Portes tells me. “So I thought this was an ideal test case. It was a frontpage headline that was completely wrong. It should be corrected on the frontpage.”

Portes adds: “The Times’ response was exemplary . . . the fact that they’d agreed on the text of the correction made it easier in some ways to make this a test case, because we weren’t arguing about the facts. We were just arguing about the prominence.”

Ipso, the press regulator created in the aftermath of Leveson, has the power to direct the prominence of a correction. This is one of what the Guardian’s media commentator Roy Greenslade dismisses as the new regulator’s “few extra bells and whistles” that distinguishes it from its predecessor, the PCC.

When compelled to publish corrections or apologies, British newspapers have traditionally buried them deep within the paper, usually perched somewhere peripheral on the letters page. And that’s not to mention the wording of the corrections – often mealy-mouthed and perfunctory.

Since Ipso was established, papers that have signed up to its code can for the first time be forced to publish apologies and corrections as prominent as the original articles. Portes’ recent tussle with The Times was the first case of a frontpage correction.

He believes the “embarrassment” of this will bring about progress in fair reporting. “In general, are newspapers taking enough care? Not as much as I would like,” he says. “But possibly more than they used to. I hope that this helps as well, because it's embarrassing having to print a correction on the frontpage.”

Shaming the press into behaving better is an approach also being used outside of the Ipso complaints process. For example, the Daily Mail lost its challenge in May against a High Court ruling that the author JK Rowling should be allowed to read a unilateral statement in an open court as part of a libel claim settlement, concerning an article about her time as a single mother in Scotland.

The Mail had paid damages to Rowling, and published an apology. But it looks like such concessions are no longer always acceptable on their own. Ordinary people, as well as high-profile figures, now have an amplified voice against the press via channels like Twitter, which makes it easier to shame and call out irresponsible journalism.

Another high-profile case brought about by Portes was the PCC’s ruling in September last year that an article about immigration in the Telegraph by David Cameron had broken the editor’s code of practice. Portes pointed out that the piece misused ONS data, mixing up “new jobs” with “net jobs”.

Another win for British newspapers' nitpicking nemesis.

Portes’ method of chipping away incrementally at inaccuracies has given him a reputation as a pedant. Niall Ferguson, the provocative rightwing historian, wrote a piece a few weeks ago for the Spectator decrying Portes, the “master of political correction”, slamming his methods as an example of lefties' nitpicking when they are “losing an argument”. "Portes may not have an economics doctorate but he is a master of the art of officious complaint," sighed the historian.

His irritation stemmed from a Financial Times article he wrote in May (“The UK Labour party should blame Keynes for their election defeat”), with which Portes took issue. He wrote to the corrections desk at the paper about one particular sentence in the article: “Weekly earnings are up by more than 8 per cent; in the private sector, the figure is above 10 per cent. Inflation is below 2 per cent and falling.”

Portes' contention was that, by using the 2010-14 nominal average weekly earnings figures, instead of the real (inflation-adjusted) figures, the statement was misleading. Actually, argued Portes, real wage growth throughout the last parliament had mostly been negative.

Following his complaint, “an often-unedifying Twitter argument” (as politely described by the FT’s Adjudication of the dispute) between the two men ensued. The paper decided to offer Portes a rebuttal, rather than to correct what it saw as “interpretations of fact”.

“A little surprisingly, Mr Portes has declined this offer,” writes the FT Editorial Complaints Commissioner. “In spite of, or perhaps because of, his somewhat rebarbative conversation with Prof. Ferguson on Twitter, he has made clear he has no interest in having a debate on the merits: he considers that the use of nominal figures was an inaccuracy of fact, which was misleading, even deliberately so.

“He elected, as he has every right to do, to appeal the editorial handling of his complaint to me.”

In the end, a clarification was published beneath the piece. But, unsatisfied, Portes dived in again, asking for another factual correction:

“And so it came to pass that Mr Portes contacted me (albeit apologetically) by email at 21:00 on Thursday 28 May 2015 to raise a further complaint about Prof Ferguson’s Article under Clause 1,” writes the Complaints Commissioner wearily in his Adjudication.

It was all resolved, but Ferguson was enraged by Portes' pernickety perseverance.

“You know, to the extent there’s an underlying truth to anything Ferguson says, it’s probably that I do have a reputation as being over-pedantic,” admits Portes. “[But] as an academic, or at least as a quasi-academic, I'd rather have the reputation as being over-pedantic than somebody who doesn't care whether or not they get their facts right. I think that I do think this stuff really matters.”

He resents the suggestion that his incessant fault-finding stems from political motives: “Ferguson obviously does what he does for a political motive, but that's different!”

And to those who accuse him of partisanship, he points out that he has taken Labour to task on some of its numbers – that leaving the EU would put 3m jobs at risk, “which is absurd”, for example, and for distorting the facts on immigration.

But is monitoring the minutiae really the way to make progress?

David Walker, the Guardian journalist and former director of public reporting at the Audit Commission, sees press manipulation of statistics more as a structural problem. “Good luck to Jonathan, he’s a great guy, making attempts to rectify distortion in reporting,” says Walker. “But it doesn’t get to the root cause, which is the club of existing proprietors who failed to address things post-Leveson. Rupert Murdoch, [Richard] Desmond, et al – as long as they remain in ownership, there will be unregulated distortion of the truth, malign use of statistics . . . bias towards a misunderstanding of statistics – let’s face it, making up stories.”

Walker adds: “Ipso isn’t the answer. The newspaper press is politically powerful and sees no reason to stop what it’s doing, and there’s a deliberate temptation to misinterpret the figures . . . There is an endemic bias of a rightwing nature.”

He advocates a stronger regulatory system and would like to see the UK Statistics Authority have a “much more interventionist” role – “some statutory right in the public media to correct statistical error”.

But Portes thinks he is getting somewhere using his methods. “I have made progress in some way,” he says. “I think at least that some of the newspapers are better off not arguing with me, because in the end, they tend to lose.”

Correction 14.30 15/7/15