The British National Party is now the main challenger to Labour in many
industrial working class seats.

That is according to the Labour MP for Rotherham Denis MacShane. Writing
in the Daily Telegraph on Friday 3rd November he said:

"Labour's problem is not with the government, but with party politics.
In constituency after constituency, membership is dropping. The BNP is
now the second party in many industrial working-class seats. Last month,
in my own constituency of Rotherham, the BNP was defeated in a key
municipal by-election, but only after a tough door-to-door campaign, of
the 2.300 votes cast, the Tory candidate got just 146."

This revelation from an MP for a constituency situated in part of
Labour's heartland that was once so secure it was called 'The People's
Republic of South Yorkshire', is in accord with similar pronouncements
from other Labour MPs and Labour Party officials. They are all saying
that in many local council seats at the elections in May, it will be
Labour and the BNP that are the only serious contenders.

http://www.bnp.org.uk