Much has been achieved by the House of Commons culture committee. Over five years and no fewer than three separate inquiries, its members have worked hard to hold News International to account for the phone-hacking scandal and to force salient information into the public domain. It is unfortunate, then, that a farrago of differences over just a single sentence in the committee's latest report threatens to undermine the credibility of the whole. Even more so given that, without the offending line, the report is still as damning an indictment of Rupert Murdoch's media empire as the company's critics might hope for.

The 11 MPs concluded not only that Rupert Murdoch "did not take steps to become fully informed about phone hacking" at his British newspapers, but that he exhibited a "wilful blindness" about what was going on in his companies. Both Mr Murdoch himself, and his son James, may have been exonerated with regards to the specific purpose of the latest inquiry – which was to establish whether witnesses at the previous investigation had misled the committee. But three other former employees (one editor, one lawyer, and one executive) were not and may now face formal censure in Parliament. More tellingly still, the committee concluded that, at a corporate level, both the News of the World and News International misled the committee in their evidence, displaying an "instinct" to cover up wrongdoing for which the directors, including both the Murdochs, should take responsibility.

It is strong stuff. And taken together, it is difficult not to draw the conclusion that the elder Mr Murdoch is "not a fit person to exercise the stewardship of a major international company". What is less clear is whether it is the job of the committee to say so. Indeed, so controversial was the charge against Mr Murdoch that five out of 11 of the committee's members refused to sign off the report as a whole, despite their support for all its other conclusions.

In fairness, the case against has much to recommend it. Not only can it be argued that, in general terms, it is the duty of shareholders, not MPs, to pronounce on the fitness of corporate executives. The condemnation of Mr Murdoch also goes far beyond the remit of the committee's inquiry. And with a regulatory probe already under way to determine whether News Corp is "fit and proper" to hold a broadcasting licence – through its holding in BSkyB – to pronounce on the issue, in such similar language, looks too much like an inappropriate attempt at influence.

That said, the naysayers may have lost more than they have gained. Committee members were yesterday trying to present the matter as an honest difference of opinion justifiably aired. But such public splits cannot but be an unwelcome distraction from the report's central, agreed and deeply excoriating conclusions.

Mr Murdoch has always been a divisive figure. The troubling aspect of yesterday's display, however, is that the split was along strictly party lines: all five Tories voted against the "fit person" amendment, the five Labour members and single Liberal Democrat voted in favour. Coincidental or not, after Monday's unedifying spectacle of the Prime Minister summoned to Parliament to account for his handling of the "inappropriate" contact between his Culture Secretary's office and News Corp, the back-and-forth over Mr Murdoch in a select committee only adds to the sense of a political establishment struggling to take an independent line.

There are many reservations about the Leveson Inquiry – not least the questionable wisdom of its running in parallel with a police investigation. But at least it promises some straight answers.