So was it the 'Standard' wot won it? Or just a sign of the times?

The paper might have sunk its teeth into Ken Livingstone but Boris Johnson's victory in the London mayoral elections owes less to a vigorous press campaign than the fading fortunes of the Labour Party, writes Tim Luckhurst

Eighty-four years ago, a title in what is now the Associated Newspapers group changed the result of a British election. Shortly before polling day in 1924, the infamous Zinoviev Letter was published in the Daily Mail. Ostensibly written in the Kremlin, it incited the British left to prepare for revolution. It was a forgery, but Labour was damaged and the Conservative Stanley Baldwin was elected Prime Minister.

Has Associated's London Evening Standard just repeated the trick in the battle for the London mayoralty between "Red Ken" Livingstone and Boris "the Blond Bombshell" Johnson?

At the Kensington headquarters of the Standard on Friday, executives must have contemplated claiming, "It was the Standard wot won it." Since The Sun's 1992 campaign against Neil Kinnock culminated in the front-page claim that it was responsible for the Conservative election victory, few newspapers have campaigned as vigorously as the Standard did against Livingstone.

Stories including "Suicide bomb backer runs Ken campaign" (16 April), "Ken's secret donation by property boss (9 April) and "A Green revolution – or is Ken just power mad?" (24 February) were calculated to convince Londoners that re-electing him would be a calamity. So was a meticulous crusade by the paper's star columnist, Andrew Gilligan, which produced damaging allegations that London Development Agency grants under the Mayor's control were given to dubious recipients.

Gilligan, once a party member and at the time of the Hutton Inquiry a hero to progressives, has been accused of treachery by Labour supporters. He can afford to laugh. Less than five years after Lord Hutton condemned him for sloppy journalism, he has won the coveted Press Gazette Journalist of the Year Award for his efforts to hold Livingstone to account.

Diligent research in Companies House reinforced by on-the-record testimony from whistle-blowers provided a solid foundation for headlines such as "Ken's adviser is linked to terror group", provoking follow-ups online and by broadcasters.

Critics say the new Conservative Mayor, Boris Johnson, is more celebrity than statesman. Well, every celebrity needs a good agent and Johnson could hardly have had a better one than the Standard's editor, Veronica Wadley. Senior Conservatives credit her with persuading a sceptical David Cameron that he could be a credible candidate. And Wadley helped convince Johnson, the Old Etonian former editor of The Spectator, to shar-pen up when initial campaign efforts faltered.

There is little doubt that Wadley dislikes Livingstone. Since February 2005, when he accused the Jewish Standard reporter Oliver Feingold of behaving "just like a concentration camp guard", relations between editor and politician have rarely been warmer than glacial. Ideological leftists who detest Associated Newspapers, and revile the Standard's sister paper, the Daily Mail, believe the Standard is to blame for turfing out Red Ken. But there is no automatic link between ideologically partisan journalism and inaccuracy. Among the Standard's editorial concerns are crime, the congestion charge and the expanding costs of the 2012 Olympics. Johnson's stance on each is close to the paper's heart, so it is not surprising that it committed editorial resources to attacking Livingstone's record. The bigger question is whether its strategy was instrumental in sweeping Johnson to victory – ie, does the press have the power to determine election results?

While newspapers can influence the way people vote, there is evidence that people prefer to read a paper they agree with. So it could be argued that the Standard's efforts to promote Boris Johnson and stigmatise Ken Livingstone were a case of preaching to the converted.

Press campaigns exert political influence more by highlighting issues than through instructions to support a particular candidate. A good example, first explored by Professor Colin Seymour-Ure, is Enoch Powell's notorious 1968 "Rivers of Blood" speech. Before Powell spoke, an opinion poll indicated that only 6 per cent of the population thought immigration was important. After two days of extensive reporting, 27 per cent thought so and 70 per cent thought the government should take a harder line.

Newspapers influence the agenda most when they highlight issues persistently over an extended period and when their stories are taken up by broadcasters and websites. The Standard could not have made Johnson more popular than Livingstone on its own. With a circulation of just 284,030 among a registered London electorate of 5.5 million, it is more of a canny lightweight than the hulking bruiser its angry critics prefer to depict.

Take-up of Andrew Gilligan's careful ferreting by outlets from the Today programme and Sky News to political blogs certainly helped to spread the impact. So did Wadley's attention-grabbing headlines and Standard billboards, which are seen by many Londoners who do not buy the newspaper itself. But in the end the Standard's "success" in seeing Johnson elected probably owes most to the same reasons that, less than a week before polling day, saw The Sun endorse Johnson as "a new and fresh champion for London".

Veronica Wadley's greatest editorial asset in the London election was a keen awareness of which way the wind was blowing. With the electorate throughout England abandoning Labour for the Conservatives, Londoners were unlikely to choose Ken over Boris. So the Standard gave its affluent, but worried, middle-class readers the political message they most wanted to hear.

Tim Luckhurst is professor of journalism at the University of Kent