Ask The Independent: Why is it that parties are not rewarded by seats in Parliament in proportion to votes cast for them?

Our experts tackle the questions that are perplexing readers

Why is it that parties are not rewarded by seats in Parliament in proportion to votes cast for them? How can this be rectified?

Robin Miller, London

On the "About My Vote" website the Electoral Commission explains that this is because UK has a first-past-the-post electoral system based in local constituencies. Each constituency has one representative in parliament, and the candidate who receives the most votes is the one that wins the seat and becomes that constituency's MP. The party that then gets the most seats in parliament forms government.

According to the Electoral Reform Society (ERS), the benefits of a first-past-the-post system and local constituencies is that it gives a strong government, it is easy to understand and that the MP is directly accountable to their constituents. But, as is pointed out in this question, this means smaller parties standing in the election can get thousands of votes around the country, but still not win a seat, excluding the candidate and their voters from power.

The alternatives to first-past-the-post are more proportional electoral systems, something that both the Liberal Democrats and Labour parties have put in their election manifestos. Whilst the Liberal Democrats do not specify in their political reform briefing what kind of "fair, more proportional voting system for MPs" they will introduce, Labour say that they will hold a referendum on introducing the Alternative Vote.

According to the ERS, this means that instead of only voting for one preferred candidate, the voters can rank the candidates according to their preferences. To win a seat a candidate must not only get the majority of votes, but they must get the first ranking in a majority of votes.

If no candidate gets an overall majority the second choices of those voting for the bottom candidates are redistributed until one candidate gets an overall majority. However, as the ERS explains, the Alternative Vote is not proportional and is in fact more disproportional than our current system. Therefore, a change to the alternative vote does not rectify the "problem".

A more proportional system, used for the Scottish Parliament, the Welsh Assembly and the London Assembly, is the Additional Member System. Each voter gets two votes, and half of the seats are allocated by first-past-the-post, whilst the other half is distributed according to the overall percentage of votes won by the party. So for example if a party wins five seats from constituencies, but their proportion of votes should have given seven seats, these two seats are topped up from the most popular candidates on the regional list. Therefore, we can see that this system is more proportional than first-past-the-post and the Alternative Vote. However, no voting system is perfect and there are more options than the three we have discussed here.

What do the Liberal Democrats need to do to join a coalition?

Tom Cubbin, Sheffield

This general election campaign has been riddled with speculation of a hung parliament and possible coalitions. The last hung parliament occurred in 1974 when Labour won 301 seats compared to the Conservatives' 297. However, this did not result in a coalition: upon the failure of the Conservative leader Ted Heath forming a coalition with the Liberals, Labour's Harold Wilson was invited by the Queen to form a minority government. In fact, post-1945 there has been no formal coalition in Westminster. The coalitions of pre-1945 only occurred at times of war, economic crisis, or as a prelude to mergers between political parties.

But this does not mean a coalition is impossible this time. As outlined in Chapter 6 of the Cabinet Office's "Cabinet Manual" (February 2010), in the event of a hung parliament "the incumbent government remains in office" until it can meet with the new parliament to assess the possibility of commanding the confidence of the Commons. There would have to be negotiations between the political leaders.

Nick Clegg would have to enter negotiations with the other parties to come up with some kind of deal. However, the Liberal Democrats have their own rules regarding joining forces with opposition parties. The Southport Conference in 1998 agreed to a "triple-lock" procedure that would prevent their party leader from agreeing any coalition deals (or any deal that would substantially affect the party's independence of political action) without the agreement of the 75 per cent of Liberal Democrat MPs and 75 per cent of the Federal executive.

Mr Clegg, when asked if he would uphold the decision made in Southport, stated: "This is not an issue of procedures. Any leader worth their salt would make sure that they take their party with them."