Ask The Independent: Do parties have to keep their election promises?

Our experts tackle the questions that are perplexing readers

Are parties legally bound to make good their election promises?

Louis Skelton, Norwich

The law lord Lord Diplock explicitly stated that: "Elected representatives must not treat themselves as irrevocably bound to carry out pre-announced policies contained in election manifestos." As such, when an elected party fails to deliver its election promises the ramifications are political rather than legal.

But does this mean that elected governments use this as an excuse not to act on their election promises? The answer would appear to be no. Research conducted by the prominent social scientist Richard Rose from the University of Aberdeen found that elected governments do generally make good their election promises.

Other evidence also suggests that more policies are followed through than not. François Petry and Benoît Collette concluded that parties around the world fulfil, on average, 67 per cent of their promises. You could argue that this is a small majority however, Petry and Collette contrast US cases, with a low average rate of fulfilled promises (65 per cent), with cases from Britain and Canada which have a significantly higher average rate of pledges fulfilled (74 per cent). It is reasonable to assume that an electoral system like that in the UK is likely to favour an elected government's keeping its promises. This is because it tends to deliver strong majorities rather than hung parliaments – making a prime minister less in hock to rebel backbenchers. In the US, the promises of a presidential candidate may be stymied by a Congress which he or she does not control.

Interestingly, there have been cases where the Court of Appeal ruled that keeping pre-election promises could be adverse to good government. In the May 1981 election for the Greater London Council (GLC), the Labour Party outlined plans to cut the fares on London's buses and Tubes by 25 per cent. It won the election and was as good as its word. However, £69m had to be raised to pay these cuts. To raise the funds, all 35 London boroughs were required to levy a supplementary rate of 6.1p in the pound. The London Borough of Bromley challenged the validity of the whole procedure. The House of Lords held that the GLC was in error in believing itself bound to implement the manifesto approved by the electorate.

How important will tactical voting be in the election?

Hollie Chaggar, Sheffield

Tactical voting must be distinguished from protest voting. Tactical voting can be defined like this: A voter prefers one party which is very unlikely to win in their seat, but strongly dislikes the party that is likely to win, and therefore votes for a third party that can win over the disliked party with the intention to keep the disliked party out of power. In the last three elections, this has been most prominent among Labour and Liberal Democrat supporters to keep the Conservatives out of power, but there is no relation between party allegiance and tactical voting. It is also often seen in by-elections.

In contrast, protest voting is like choosing 'none of the above' option, and either spoiling the ballot or voting for a party that stands no chance of getting in to government in order to show dislike for the system. Tactical voting is an issue particular to the UK's "first past the post" electoral system .

It is difficult to assess the effects of tactical voting, and academics do not agree on the matter. According to Professor Gerry Stoker at the University of Southampton, the likely effects on either the turnout or the result of the election are limited. This is because the voters who vote tactically are few, approximately 9 per cent of the electorate, according to the UK General Election Survey.

In contrast, Dr Stephen Fisher at the University of Oxford argues that these 9 per cent can have substantial effects on the outcome, and in recent elections they have affected the results of about 40 seats. In a tight election like this one – if Dr Fisher is right – it could be crucial.

Does celebrity support affect whether people vote for a certain party?

Chloe Starling, Southampton

It is difficult to assess the effect of one single variable on the result and turnout of an election, as many different factors influence voting behaviour. However, as Gary Barlow became the latest celebrity to be wheeled out by the Conservatives, and J K Rowling nailed her colours to the mast of Labour, political parties must believe that there is something to be gained from "celebrity politics".

Academics see two reasons for the collaboration between politicians and celebrities. Firstly, the logic behind the success of celebrity politics is based in Dr Jennifer Lees-Marshment's argument that politics is marketing, and so is celebrity. Therefore if the two are combined it should be a recipe for success. Secondly, celebrities might attract voters who do not identify with politicians, and would therefore be remote from the normal political marketing by the parties.

There is evidence of this working in practice. One study conducted by Cartwright and Moore on the US 2008 primary elections suggests that Oprah Winfrey's endorsement of Barack Obama served him at least 1 million votes. But what is less sure in a British context is whether the likes of Michael Caine will have a similar effect.