On Thursday 5 May, Martin Radford will pop out of his London flat overlooking the Royal Victoria Dock in the capital's east end and stroll next door to the polling booth to have his say in the UK's first national referendum in 35 years.

Radford, a retired restaurateur who serves as a magistrate, has received leaflets from both the yes and no campaigns and concludes that switching to the alternative vote is a good idea. "It will be a fairer way of voting," he says.

The fear is that Radford will be in the minority of Londoners when it comes to casting a vote for or against replacing the first past the post system, with turnout predicted to be as low as 15% among an eligible electorate of more than five million.

Less than 50 metres from Radford's door, the referendum result will be announced on 6 May in the Platinum Suite of the expansive ExCeL convention centre.

Counting officers across 440 local areas will feed the results to 12 regional hubs around the UK, which will be relayed to the Docklands venue for an event costing the Electoral Commission £172,500, including a dummy run.

Getting out the London vote is seen by some as crucial to the final outcome. The no campaign, still ahead in the latest opinion poll, is taking nothing for granted, launching campaign material specifically designed to woo Londoners. The yes campaign is also working hard to garner support in London.

Tony Travers, director of the Greater London group at the London School of Economics, says London has an "enormous amount of power" in the AV vote because of the capital's demographics.

"There is no doubt that the polling so far suggests that London is more enthusiastic about AV then the rest of the UK and that is almost certainly to do with the relatively young population in the capital," he says.

The downside is that younger people are less likely to vote, he says. "At some level, it can be seen as a vote between the young and the less young. Electoral reform is linked in people's minds with other causes. The younger you are, the more likely you are to want progressive votes so it looks as if younger voters associate AV with a more progressive vote."

It was in London, just under a year ago, that hundreds of mostly young people turned out with purple banners in Smith Square in Westminster two days after the general election to urge Nick Clegg and fellow Lib Dems holed up in party talks to secure "fairer votes" as part of any coalition deal with the Conservatives.

But the impact of other policies that were accepted in the trade-off by the Lib Dems may counter support from the young, according to Siobhain McDonagh, the Labour MP for Mitcham and Morden. She believes many young Londoners who do come out and vote will want to give Nick Clegg a "bloody nose over tuition fees".

A strong supporter of the No to AV campaign, McDonagh believes the case for electoral reform is not high on people's minds. Her experience suggests many do not seem to understand what they are being asked to vote for. "I have been inundated with calls for the last five days as postal votes have dropped on mats, with people saying, what is this about?" says the MP.

As a member of a party split on the issue, misunderstandings leave her in a tricky spot. " They say they want to vote Labour or that they want to vote for me." But she is clear which way the wind is blowing. "More and more people say they are coming for no."

Boris Johnson, the Conservative London mayor, who was elected via the supplementary voting system, a cousin of AV, is urging people turn out to vote no, while his predecessor in City Hall, Ken Livingstone, who is seeking re-election next year, is pressing the case for reform.

Professor Michael Thrasher, an elections expert, says: "If the turnout is as low as 15-20%, then the people most likely to come out and vote will be those people over 55 that live in London." And he says those people, according to polling, are most likely to want to retain first past the post.

A "mock AV" poll conducted in England and Scotland by YouGov for the Institute of Public Policy Research in the first week of April revealed that Londoners were split down the middle, with 34% saying they would vote yes, and 35% saying they would oppose change.

A national poll by ICM for the Guardian published last Monday showed the no camp had a 16 point lead.Despite the supplementary vote system used to elect the London mayor, Londoners were more likely (37%) to believe they would find it difficult to vote using AV than respondents elsewhere. More (9%) of London respondents said they would not vote at all, but there were also more in the don't know camp than anywhere else in the country (23%, compared with a total figure of 17%). The findings suggest many hearts and minds may still be there for the taking in the battle for the London vote.