Candidates line up for Croydon North by-election

Malcolm Wicks had a majority of 16,483

The story of Croydon reflects the story of London, where demography and diversity have been transformed over the last half century.

The area was solidly Conservative from 1955 until a boundary re-organisation in 1997.

The more urban-north of the previous constituency was hived off and Malcolm Wicks became its first MP. He was there for 15 years until his death, prompting this by-election.

His majority at the 2010 election was 16,483, the 11th largest in the capital.

Probably the only thing close about Thursday's by-election has already happened - a contest between two leading south London municipal players for the Labour nomination.

Prized Labour citadel

Lambeth Council leader Steve Reed won the party's backing for this prized Labour citadel, defeating Val Shawcross, a former leader of the local Croydon Council, currently a member of the London Assembly and deputy to Ken Livingstone during his failed resurrection bid this year.

Labour present Reed as one of a new brand of competent town hall leaders who have adjusted to - even embraced - cuts and austerity by trying to re-shape council services.

In Lambeth, they've called it a "co-operative" way forward.

Lee Jasper offers an extra dimension of uncertainty

The Conservative challenger Andrew Stranack is Croydon-born and has an interesting recent back story.

He gave up his job working for the council in 2001, and spent six years on a local housing estate living on a low income and doing Church-based community work.

The Liberal Democrat candidate Marisha Ray is a former IT professional who currently advises the board of a London NHS Hospital trust.

But it's the presence of Respect which offers an extra dimension of uncertainty, and not simply because of George Galloway's success in Bradford.

In Lee Jasper, controversial former adviser to Ken Livingstone, Respect have chosen a charismatic figure whose involvement in police community relations and anti-racism campaigns over the years made him a well-known figure in neighbouring Lambeth.

Polling stations are open between 07:00 and 22:00 GMT on Thursday 29 November