Colne Valley is a marginal constituency and one of the few seats which could be won by any of the three main parties.
Labour's Kali Mountford, who has represented the area in Parliament since 1997, is standing down at this election for health reasons. She finished 1,501 votes ahead of the Conservatives in 2005, with the Lib Dems a further 4,200 behind. Colne Valley is 27th on the Tories' list of target seats and 40th for the Lib Dems. The Conservatives consider the seat a "must win" if they are to form the next government.
Debbie Abrahams will try to hold the seat for Labour against Jason McCartney of the Conservatives and Lib Dem Nicola Turner.
The constituency name is misleading, as the seat includes not just the Colne Valley, but also the Holme Valley, Lindley and Crosland Moor. The seat takes in numerous towns and villages, including Slaithwaite, Marsden, Golcar, Linthwaite, Honley, Holmfirth, Meltham and Milnsbridge.
Latest census figures show that one in five people in the constituency is over-60 and one in four is under-18.
The beautiful countryside of the Colne Valley constituency is best known to the world through long-running BBC series Last of the Summer Wine, which is set in Holmfirth.