Of swinging voters and spotty boys, Galloway Girl, carnal joy, and the poor old impotent voter on a blind date with Miss X

This is our big democratic moment, right? Vox populi, vox dei. We - the electorate - shall open our mouths and the thunderous roar of our voices shall send the almighty tumbling, OK?

Not with our electoral system, unfortunately. For all the difference our votes will make, three quarters of us might as well stop talking to the pollsters, resist the temptation to follow the campaign and stay at home on May 1. Under our first past the post system, the fate of 150 of our 659 seats - less than a quarter - will decide the election: the others are pre-ordained shoe-ins for the major parties. And as individuals too, the vast majority of British citizens are as powerless to affect the course of polling history as we are to influence the outcome of World Cup soccer matches.

But we care, most of us. And we'll still vote and take sides and argue in pubs and fight over dinner tables. So this is a guide to help those who may be electorally impotent but remain interested to recognise the truly influential - those whose actions really will decide who ends up ruling the nation on 2 May and beyond.

Swing voters and regional deviants

Some voters do matter, voters like Worcester Woman (no relation to Bob Worcester of MORI, the Grand Old Man of polling), a thirtyish middle-class Mum to be found in concentrated form in key seats; or Willy Wurzle, a West Country elector, whose greater than average attachment to the Liberal Democrats could damage the Tories in a string of Devonian and Cornish seats, boosting Paddy's post-election bargaining position: and finally - Galloway Girl, who has it in her power to shut the Conservatives out of their remaining few seats in Scotland.

Tories

John matters. If he stops believing for one instant that victory is still possible, then defeat could turn to rout. His key allies in this attempt at political levitation are not his cabinet colleagues (by and large they are fatalistic), but Danny Finkelstein and the Tarquins.

Head of research at Central Office, the flame haired Finkelstein is the brains behind the Tory strategy, the writer of its "story": so the manifesto and campaign are essentially Finkelstein's monster. The Tarquins are his lab assistants.

But there is no guarantee that the post-election Leadership Contenders (Portillo, Howard, Redwood, Hague and Dorrell), will keep to the story if all appears to be lost. Watch out for constructive additions to the party's thinking on taxation, welfare and - of course - Europe. Which is where Sir James Goldsmith comes in. For once the phrase "but they have no-one else to vote for" does not apply to disgruntled right-wing Tory supporters. They have Jimmy, and many of them could take that option.

Labour

Tories hope that the Gang of Four (Blair, Brown, Cook and Prescott) will suddenly start to behave like the Albanian synchronised swimming team. If they do, Labour could conceivably lose - which is why they'll keep it sooo tight. Others could mess up, like The Boychiks - Labour's spotty but dynamic answer to the Tarquins - who advise most major figures and have their own contact with the press. Look out for Tim Allan, various Milibands, Ed Balls, Derek Draper and other talented teens.

Should the campaign become difficult Tony Blair will fall back on key influences. His mentor, first employer and Lord Chancellor-designate Derry Irvine will steady him. He may also seek consolation and wisdom from Our Lord. And, at the other end of the spectrum, there's Peter Mandelson.

The media

Always there to ask the first question at the campaign press conferences, to pass instant verdicts of success or failure on the speeches or pronouncements of the politicians is Robin Boulson, the sleek and well-fed composite political editor of BBC/ITN/Sky News.

Do not expect Robin to tell Michael or Trevor in the studio that it is only five seconds since Mr Blair or Mr Major sat down, so he hasn't had time to fully digest what was said. Oh, and dear Rupert still has four papers to declare.

Hijackers

Everyone will get very fed up with policy and manifestos and statistical warfare, and it is then that the long campaign stands in danger of being completely sidetracked by someone or something exotic.

Good bets are Mohamed Al Fayed, Christine Hamilton - the terrifying and murderous looking wife of sleaze-linked Tory Neil Hamilton (what will she not do to prevent his downfall?).

Then there's Miss X or Master Y - past sharers of illicit and risible carnal joy with MPs or ministers. Princess Diana, who will declare for Labour before the month is out (just you mark Ol' Davey's words), and Swampy, the collapse of whose tunnel under the runway at Manchester Airport - and the subsequent loss of BA932 taxiing along for take-off to Marbella - could swing the election back to the Conservatives.