Celebrity political endorsements are nothing new. Way back in the 1920s, Republican Presidential Candidate Warren Harding gained the support of singer and entertainer Al Jolson, who released a song entitled "Harding, You're The Man For Us". John F Kennedy also palled around with Frank Sinatra and Marilyn Monroe, but does this really have any particular effect?
According to a study by political science professor Anthony Downes the answer is sort of yes and no. In other words, a lot of it hinders on people's pre-existing views of both the celebrity and who they endorse.
If someone already supports a party, they are unlikely to suddenly be swayed to another just because a celebrity says so, in fact they'll most likely just have a more negative opinion of the celebrity instead. If they agree with them, the opposite happens and a person may feel some more affinity with both the party and the celebrity.
Essentially, at best it's a bit like preaching to the converted when it comes to those with already decided political opinions. Celebrities might have some more sway when it comes to undecided voters, especially those who are younger and may not know where to start when it comes to politics.
In this instance, a celebrity endorsement might actually help a political candidate. That all depends on the actual celebrity themselves though. It's easy to assume that there are large swathes of the younger population who couldn't care less that Gary Barlow supports David Cameron, while support from a member of One Direction might be a bit more influential.
In the end, once people actually get to grip with a party or candidate's policies, it's unlikely the celebrity promotion will hold if the person finds they don't agree with any of them.
There are other issues at play which can still have an effect on the political landscape though. While some celebrities are courted to offer their support, some give it without request and this can be a PR problem for a politician.
For example, no politician is going to want the support of a disgraced celebrity. Imagine if Rolf Harris, once released from prison for sexual offences, gave his support to David Cameron. The Tory party would have to spend its time distancing itself from Harris, while Labour could use it as a stick to beat Cameron with.
In the end though, past a bit of a negative publicity, it's unlikely an unrequested message of support is going to do much damage to a party nor significantly influence the public. If UKIP can survive its own members coming out with vile views, then a party can survive non-members doing the same.
Of course, celebrities don't have to endorse actual people or parties, there's also ideas and movements which they can support and it's here where they have a much stronger influence.
Russell Brand is a perfect example of a celebrity who has entered the world of politics, but instead of becoming a politician, like Arnold Schwarzenegger, he's involved himself in activism instead. By refusing to endorse anyone he has instead endorsed the view that the political system itself is a failure and that other means of change are necessary. A view that people will find easy to agree with due to their lack of trust in politicians.
Brand is essentially an oxymoronic mix of apathy and energy. He has encouraged people to involve themselves in politics, but to also actively eschew politicians themselves. While his actual views are nothing new, they are being absorbed by a lot of people.
Bar a spirited anti-UKIP speech from Dennis Skinner, when was the last time someone espousing proper left wing views other than Brand was so heavily talked about and shared on social media? At a stretch there's Owen Jones and Mark Steel, but they've not gained the reach and attention Brand has.
It's this mass dissemination of ideas that can influence people, especially young people, to reassess how they view the world and possibly consider new alternatives. While people may not agree with Brand's finer points, they are in tune with his general message that mainstream politicians have failed the people, something that UKIP themselves have tapped into.
So has Brand changed the political landscape? It's hard to say, but his presence has at least been noted. You also cannot deny that the publicity he brought to the New Era Estate campaign contributed to their victory. One success, no matter how important to a small group of people, is not exactly a political earthquake though.
So what if Brand was to actually endorse a candidate, such as Natalie Bennett of the Green Party? It could end up going one of two way, it could lead to new support for the Green Party as those following Brand agree that maybe there is actually someone to vote for. The other outcome could be people seeing him as betraying his previous views and supporting the 'establishment'.
All in all, celebrities have more sway when it comes to giving publicity and that lends itself more to individual movements or campaigns. A savvy up-and-coming politician could probably use a celebrity in a positive way to get themselves known but, for the most part, the influence of celebrities influence the periphery of politics more than the centre of it.