It's low, it's dirty, and it's personal

Here is an early sketch of a planned Labour Party broadcast. A line of enormous pigs are seen in gory close-up, messily feeding. The image is intercut with footage of Conservative MPs in the House of Commons. MP - snout - MP - snout - MP's soundbite - pig's grunt - soundbite - slaver. A well-known actor's voice intones: ''This has been the greediest, sleaziest Government in modern British history...''

Here's another rough cut. John Major is shown in action during the last election campaign, making his now-notorious promises on taxation and the economy. ''A serial liar - catch him before he strikes again'' snarls the voice. Or another: clips of Asil Nadir, Octav Botnar and Kamlesh Pattni, all of them past Tory donors and ''wanted for questioning'', and then of Nazmu Virani, jailed in 1994. ''Which party is really the villain's friend?'' sneers the voice. ''Which party pocketed their cash?''

All right, I made them up. I have no idea if there are Labour-supporting copy-writers working on these or similar lines in some Soho ad agency.

My point is only that the Conservatives ought to be careful about the kind of personalised attacks being launched against Labour, however tempting they may be. A certain mutual restraint is the foundation of respectable politics. The Central Office billboard campaign against Harriet Harman was probably irresistible; Michael Heseltine's assertion that Labour is ''traditionally on the side of the villain'' should have been resisted. If I am concerned about the Government's legislation on asylum-seekers, does that make me the mugger's mate? Apparently it does.

Conservative strategists will retort that they are only using the gap between Labour actions and rhetoric to point up policy failures, a legitimate tactic. A traditional one, also: attacks on left-wing leaders for their hypocrisy are as old as progressive politics. Fox, Gladstone, Lloyd George, Wilson - all would have failed the Central Office ''do as I say, not as I do'' test. All were far grander in their private appetites than in some, at least, of their demagoguery.

Labour could equally well argue that by reminding voters of the misbehaviour of individual Tory MPs and of past embarrassments over party funding, they were ''really'' exposing what happens when one party has been in power for too long. They may also consider that the public, faced with the crimes of sending a boy to a grammar school or, alternatively, misleading them about their taxes, may regard the latter as worse.

But the problem is the tone of the attacks, not the content, and politicians know this as well as the rest of us. Everyone can spot the slither into the slime pit. When Michael Howard tries to smear Labour as pro-crime and Labour attacks him as a cynical racist, both sides know what they're doing.

And the frustrating thing is that the crudest, most bitter attacks really are a diversion. There are vital gaps and political failures to be attacked and highly effective ways of attacking them that don't involve nastiness.

For instance, the best Tory response to Labour's problems over selective schools is to try to jemmy apart the inconsistencies in Opposition policy and offer something more coherent themselves. This they will certainly try to do. Ministers and advisers are already preparing a switch in policy on schooling, so that pupil selection will be openly embraced and defended, rather than being sneaked into the state system, as now.

Some members of the Cabinet would like to bring in selection with vouchers too, but John Major is still uncommitted. A likelier outcome is that the Tories will use their election manifesto to propose an extension of selection along with the expansion of grant-maintained schools. There would be no return to the 11-plus exam but there would be a promise of new grammar schools and new specialist schools in a more diverse system.

If the polls are anything to go by, the electoral impact would be favourable: a Harris poll for the Daily Telegraph earlier this month found 54 per cent in favour of a return to full selection, as in most of Britain's competitor countries. But such a shift would also put pressure on Labour's logic. The party believes in streaming and setting inside schools, dividing children by classroom. How different in principle is this kind of selection from having different schools? That is the kind of hard-edged political attack a confident Conservative Party would be relying on, rather than the somewhat petty tone of the anti-Harman campaign.

In a similar way, the Labour Party has a whole ammunition depot of devastating material to use against the Conservative tax record without stooping to calling Major a liar. Personal or abusive campaigning is bad for all politicians because most voters listen to it and believe both sides; they agree that Labour are hypocrites and that the Tories are sleazy. Their disgust is general to the activity, not specific to one party or another.

Here, though, we come to the final layer of political double-think. Most politicians would, if asked, agree with almost everything in this column. In private, even the most senior people deplore the rise of abusive soundbites, profess to be despairing about the level of exchanges in Prime Minister's question-time and say they are deeply worried about the public's cynical dismissal of democratic politics.

But then they go out and start kneeing one another in the privates, returning desperately to the vituperation like alcoholics going back to the bottle. They say they abhor recent developments in American politics, where ''negative campaigning'' reigns unchallenged, and millions are spent on bilious attacks on the opponent's morals, record, intelligence and motives. But every indication is that the 1996-97 campaign in Britain will be similar and designed to be similar; the main parties are even sending their apparatchiks off to Washington to watch and to learn how it's done.

Why? It seems the whole self-regarding crew who have tried to make democratic politics into a pseudo-science have finally cowed the politicians. Ministers and shadow ministers regard the ad-gurus, the pollsters, the spin-philosophers and the campaign strategists, particularly if they are American, or have once met some Americans, with awe. Some of these political parasites have damaged the reputation of democracy, shallowed debate and produced horrible own-goals. I think a few fresh-sounding arguments from politicians, delivered in clear English, would be vastly more effective. But in our scientific age, these people are now regarded as gods.

Or at least as experts, which is better. Few politicians care nearly as much for the reputation of politics as they do about defeating the other lot. If they are told negative campaigning works, they will giggle and assent to stuff which would make them, as private citizens, deeply uneasy.

I prefer to end such columns on an optimistic note. But on this subject it is impossible to be jaunty: first indications are that we are in for a filthy, degrading campaign. If the party leaders go that way and then, when it's over, complain about the dangerous cynicism infecting our democracy, then we should treat their protestations with contempt. That would be one act of collective hypocrisy too far.