The chart below shows the 2010 general election result for every seat in Great Britain with the colour showing the party that won . Dots that are nearer the apex of the triangle had a higher vote share for Labour in 2010, those closer to the bottom left; for the conservatives while the bottom right corner shows the share for all other parties.
You can already see in this chart where the battlegrounds lie as the colours meet where one party is getting about 40 per cent of the vote.The two biggest concentrations of dots are around the lines where the Labour seats meet the Conservatives and where the Conservatives meet the Liberal Democrats. There’s also a handful of seats where Labour were competing with either the Scottish National Party, Plaid Cymru, the Greens or the Liberal Democrats.
The chart below shows the same but for the four battlegrounds that the FT has flagged as seats to watch in 2015.
The Labour-Tory marginals are by far the most numerous group, however, and will probably have the biggest impact in determining the overall shape of the government the following the general election, but the other battles will decide the junior coalition partner.
Labour are fighting a battle on two fronts, not only against the Conservatives in what are mostly ex-industrial midlands constituencies, such as Birmingham Edgbaston and Broxtowe in Nottingham, but also against the SNP in most of Scotland.
The Liberal Democrats will also have to hold off the SNP in their Scottish seats but their biggest threat is the Conservatives in a set of affluent seats, many of which are in the southwest, such as Torbay and Wells.
Lastly, the Conservatives are facing a challenge from Ukip in many of their more working class seats, along the east coast like South Thanet, where Nigel Farage is standing, and Boston and Skegness.