Russell Brand and Delia Smith do not seem like natural bedfellows. They have rather different target audiences. ‘Anarchical’ Brand is one of the UK’s most followed tweeters, while ‘sensible’ Delia is the nation’s bestselling author of cookery books. They, however, have at least one thing in common. Both celebrities recently endorsed the Labour Party.

Brand and Smith are not the only ones: Steve Coogan appeared in Monday night’s Labour Party Election Broadcast. Snooker star Ronnie O’Sullivan was filmed playing pool with Ed Miliband and gave his backing to the Labour leader. Actors Martin Freeman and David Tennant have also appeared in Election Broadcasts for Labour this campaign, while comedian Eddie Izzard has yet again been a mainstay of the Labour campaign.

If Labour has been busiest in securing celebrity backers this election, they have been by no means the only party doing so: ex-footballer Sol Campbell for the Tories; actor Brian Cox for the SNP; romcom-fave Hugh Grant for the Lib Dems; and model Lily Cole for the Greens. All have played a part to varying degrees in this election campaign.

It’s an interesting bunch of people for sure, but is the general public really swayed by such endorsements? Here are three reasons why celebrity endorsements might just matter.

1) People don’t trust politicians

It remains a sad but true fact that politicians are amongst the least trusted people in society. Polling published by Ipsos MORI in January found just 16% of Britons trust politicians to tell the truth. They lag behind other popular societal bogeymen including estate agents (22%) and bankers (31%). So it is entirely understandable that, when politicians want to get their message through, they often turn to alternative messengers. The logic goes: “Don’t believe us when we say we’ll look after the NHS? Well listen to Delia Smith!”

2) The power of social media

Let’s take Russell Brand. The traditional media outlets scoffed when Ed Miliband was photographed arriving at Brand’s apartment to film an interview with the previously abstentionist and ‘revolutionary’ comedian. But consider the reach Brand has on social media, where many young and otherwise disengaged potential voters reside: 9.6m followers on Twitter and over 1m subscribers to his YouTube channel. Ed Miliband has fewer than half a million Twitter followers, while the Labour Party YouTube channel has only 11,000 subscribers. The two videos Brand has posted featuring his interview with Miliband and his subsequent endorsement of a Labour vote in England have had a combined 1.7m views (and counting). Viewed in this context, it is hardly surprising that Miliband felt it worth courting the ‘Brand vote’ – Miliband’s message will have reached hundreds of thousands of voters who may otherwise have paid little attention.

3) Every vote matters

Cliché alert, but this election is ‘on a knife edge’. It is also ‘too close to call’. And ‘could go either way’. So every vote that parties can squeeze out of the electorate has the potential to make a real difference. A 2010 academic study at the University of Bath found that “low political salience respondents were significantly more likely to vote for the political party when a celebrity endorser is used.” In other words, those who engage with politics the least are most likely to be influenced by celebrity backers. To go back to the Russell Brand example, if even 1% of those who watched his videos feel more inclined to turn out to vote Labour as a result, it could make a difference in some key marginal seats. The fact that Brand’s core audience is in an age bracket with traditionally the lowest level of turnout means his endorsement may potentially be particularly useful for Labour.

So there is at least some sound, logical underpinning of the use of celebrity endorsements in election campaigns, particularly in close elections where trust in politicians is low and driving up turnout amongst otherwise disengaged groups could make a difference.

None of this means that the endorsements of some actors, a celebrity chef and a snooker player are necessarily going to swing it for Labour on Thursday. And any impact they might have will be incredibly hard to trace anyway.

But we should not entirely discount the possibility of a Russell Brand effect.