Party in the last chance saloon: It's been a spectacular show: a cabinet minister, an actress and a tabloid editor in the leading roles, the whole nation as audience. Maggie Brown reports

Phew] A week is a long time in journalism. And what a scorcher it has been. The story of David Mellor couldn't have been better if you'd made it up. It sold extra papers and, despite the distress he may have caused his family, the disclosure has been deemed to be 'in the public interest'. On Wednesday, the Press Complaints Commission, mindful of how the public appears to feel about these matters, said that the private lives of politicians are matters of public interest (its judgement was not about the Mellor case in particular, but such matters in general).

The week has had two leading actors and both played their parts to perfection: Mr Mellor, who by his behaviour, his choice of woman and his choice of observations to reporters, has aroused a combination of fascination and indignation that cannot be denied, and Kelvin MacKenzie, editor of the Sun, who on Tuesday (as did the Independent) reminded readers that the tabloid press had no monopoly on disclosure about the sex lives of politicians: Conservative ministers were keen to smear opponents when it suited their book.

Mr Mellor, usually so suave and confident in his dealings with the outside world, has managed to alienate public sympathy with every move he makes. If his aim was to illustrate why a privacy law is desired by politicians for their protection, he could not have done better.

First, his judgement, as QC, cabinet minister and Privy Councillor, has been called into question; second his choice of dalliance was too damn exciting: full of exotic attraction, but too much of a dangerous distraction from the good folk of his comfy Putney constituency, the prosperous milieu of his anguished parents-in- law, and the well-bred ranks of parliamentary secretaries and research assistants which usually provide the first call for politicians' solace.

At best, Ms de Sancha has indiscreet friends. At worst they are treacherous. She may have trained as a classical actress, but she also starred in what has been called a 'soft-porn' film in which she made love with a pizza delivery man. This we know because the Sun carried the pictures yesterday.

But most damaging in the wider world has been the way Mr Mellor is perceived to have tried to use his family as a last-ditch attempt to protect his career. In a plea for the hounding to stop, he said on Monday: 'I am particularly concerned about my two young children', as if the press, rather than his own behaviour, was causing them damage. This sub-plot was taken up by none other than his own mother- and father-in-law who gave a series of distraught interviews to tabloid newspapers. They called him a 'dopey idiot' and told a pathetic tale of how sobbing Judith, Mr Mellor's wife, had been left to find out about the affair, on her own, on Saturday night. By yesterday Mr Mellor had rounded on them, warning them they would never see their grandsons again. The family was at dagger's drawn, and Mr Mellor's ability to ride out the storm looked doomed.

You can pinpoint when the public mood against Mr Mellor became clear. It was on Tuesday, when the balance of calls to the BBC's Call Nick Ross was in support of the press's role. This clearly astonished both Nick Ross, used to the traditional crusty Radio 4 audience, and Bill Hagerty, editor of the People, who had risen from obscurity by breaking the Mellor story. You could almost hear him relax on air.

This was the situation as Mr MacKenzie unleashed what was to be the knock-out punch. It came with the revelation that, during the general election campaign, a cabinet minister had rung his office with a list of names and addresses of women alleged to have had affairs with Paddy Ashdown. Mr MacKenzie had set his reporters on the trail, and found the allegations to be false. 'What a two- faced bunch so many of them are,' he wrote.

The Cabinet rushed to deny it en masse, as Mr MacKenzie resolutely stood his ground. He was backed up by an unusual but valuable ally: Anthony Bevins, the Independent's political editor, confirmed that he had been told, by a cabinet minister, of a similar plot. This is an odd little twist: the Sun dislikes the Independent which it slags off with ringing Sunisms: ('a parrot wouldn't deign to have it at the bottom of its cage' and that kind of thing passim).

The Sun, Britain's largest selling newspaper, and Mr MacKenzie, its long-serving editor, are fervent supporters of the Conservatives. After the election the paper crowed, 'It's us wot won it'. But whichever cabinet minister rang the Sun with his tips about Mr Ashdown in the run-up to the election made a serious blunder. For Mr MacKenize, as with Rupert Murdoch, his proprietor, is no establishment lackey. In fact, he views the top crust with undisguised animosity. He has no interest in protecting the great and good, let alone in hobnobbing with them. Unlike Sir David English of the Daily Mail or Sir Nicholas Lloyd of the Daily Express, he is not a Tory knight; this week he was a Tory nightmare.

His oft-stated attitude is simple: the readers of the 'currant bun' have a right to know about the affairs of the high and mighty, and no amount of humbug about 'not in the public interest' will persuade him otherwise. Not if it's his story anyway. (He took idiotic exception to the Independent disclosing facts about the youthful years of Virginia Bottomley).

Yesterday, the Sun made another shrewd point about the argument for the protection of privacy as put by politicians. They make a fuss when a politician's misdemeanours are publicised, but don't give a tinker's cuss when it's not one of them.

When Peter Shilton, the former England goalkeeper, was caught with a woman not his wife and written about, though much fun was had by fans on away grounds, Westminster was undisturbed.

On Sunday, when the Mellor story first broke in the People, it was crystal clear that serious and agonised commentators were uncertain how to react. The public interest justification - that Mr Mellor promoted a happy family image - was felt to be a bit thin. The methods used to bug his conversations with Ms de Sancha also looked sneaky.

The doctrine that the public have a right to know about the disorderly private lives of those who purport to rule them was advanced, but not with gutsy conviction.

Nor was it clear which way the Press Complaints Commission, especially its lay members, would jump. By Wednesday, when the Commission met, it was very clear. The Mellor story was held to be

in the public interest. And its chairman, Lord McGregor, added that privacy laws would be an infringement of the freedom of the

press.

The depredations of the tabloid press are often inexcusable; their lust for sensation sometimes leads to the courtroom and/or monster libel actions (Elton John and the Sun was a pounds 1m classic). But in this particular case the story is true and the public's position is clear.

Mr Mellor is the minister in charge of vetting press behaviour and for overseeing any move towards a privacy law. It was he who told the press to watch out because they were drinking at 'the Last Chance saloon'. This week the drinks are on him.

(Photograph omitted)