The claim

“Labour will seek to steal the election, relying on an electoral system so biased in their favour that 35 per cent of the vote could deliver them 55 per cent of the seats.”
Justine McGuinness, 7 October 2014

The background

Readers have asked to us to check this eye-catching statistic, which popped up in a Lib Dem conference speech today.

The speaker was Justine McGuinness, an activist from West Dorset Lib Dems who is probably better known as a public relations consultant.

It’s well known that many Lib Dems believe the way Britain chooses MPs unfairly penalises the smaller parties – but can our electoral system really be so unfair?

The analysis

Ms McGuinness’s figures are absolutely right. They come from the 2005 general election, when Tony Blair’s Labour won 35.2 per cent of the popular vote, compared to 32.4 per cent for the Conservatives.

Despite the fact that the difference between the total votes cast for both parties were very small, Labour ended up with 355 seats and the Tories got just 198. That’s 55 per cent compared to 30 per cent.

The website politicsresources.net handily puts the results of every election since 1945 into graphs. It quickly becomes clear that there is a historical bias in favour of Labour.

Labour tends to get more parliamentary seats for a smaller percentage of the popular vote.

The 2005 election is a memorable recent example of the mismatch, but there are worse cases. In the general election of February 1974 Labour actually got very slightly fewer votes than the Conservatives nationally but ended up with more seats.

How can a party win an election without getting the most votes?

In our first-past-the-post system, the winning candidate in each of the 650 parliament constituencies is the one who gets more votes than anyone else.

A landslide victory or a win by a handful of votes each leads to one MP being returned to Westminster. Votes for candidates who come second or worse are “wasted”.

It follows that parties do better when they win with narrow victories rather than thumping great majorities. More votes count towards a victory rather than going to waste.

Parties do better when they win seats that have fewer voters in them and where voter turnout is lower.

From the 1990s on in particular, these factors have increasingly favoured Labour, according to politics professor John Curtice of Strathclyde University.

Despite independent reviews of the boundaries of parliamentary constituencies, seats won by the Conservatives in 2010 had about 3,700 more names on the electoral register than those won by Labour.

Labour tends to win in urban seats where there is a low turnout, whereas the Conservatives win in higher-voting suburban and rural areas.

Prof Curtice reckons the system has become so biased that, where Labour won a safe majority with a lead of just three percentage points in the popular vote in 2005, the Tories would need an 11-point lead over Labour to secure an overall majority.

Bad news for UKIP?

The importance of the geographical distribution of a party’s support means it may prove difficult for Ukip to pick up seats in 2015, even if they win a significant chunk of the popular vote.

As we found in an earlier FactCheck, two different methods of predicting voting patterns in next year’s election forecast that Nigel Farage’s party will fail to return a single MP, despite possibly attracting more than 10 per cent of total votes cast nationally.

In fact, we found that it was possible for Ukip to get a bigger share of the national vote than the Lib Dems (like 17 per cent versus 13 per cent) and still fail to win a single parliamentary seat.

This is probably because Ukip’s support is spread over too wide a geographical area. It is possible for smaller parties to win seats, but only when a lot of their support is more concentrated geographically – like the Greens in Brighton.

Rights and wrongs

Not everyone agrees that first-past-the-post is unfit for purpose. It tends to penalise the smaller parties, as we have seen, but you could argue that having a straight choice between two parties is preferable if it leads to fewer hung parliaments and coalitions.

However, the Institute for Public Policy Research points out that if our voting system is supposed to discourage support for smaller parties, it is failing.

The think tank finds that since the 1950s, votes for the two biggest parties combined have fallen from more than 90 per cent to 65 per cent, while support for the third party (Liberals, Alliance or Liberal Democrats) and the “other parties” have increased dramatically.

So not only is the current system unfair, it is failing to deliver its promise of strong one-party government, according to the IPPR.

The verdict

The current system is indeed biased in favour of Labour, although most academics say this is the result of historical accident rather than deliberate “gerrymandering” by Labour.

While the Conservatives appear to be seriously disadvantaged by current arrangements, most Tories remained firmly in favour of first-past-the-post and campaigned against the alternative vote system in the 2011 referendum.

It’s also worth noting that the Conservatives wanted to redraw boundary constituencies before 2015 – which would have reduced the pro-Labour bias Ms McGuinness is complaining about. But the Tory plans were defeated when the Lib Dems voted against their coalition partners on the issue last year.

The Lib Dems have traditionally favoured scrapping first-past-the-post, but they might find that it keeps them well clear of Ukip in terms of parliamentary power, even if the Eurosceptic party becomes Britain’s third biggest party in terms of the popular vote.