This is what the core Labour votes are worried about
Even though Brown uses BNP style slogans, the BNP are the party that is tapping into the disillusioned working class voter who has lost their job and has to watch while other Europeans are employed on British contracts.
The best the government can offer is
a) British workers are employed abroad (not car workers I might add)
b) Get on your bike and find work in Europe (Auf Wiedersehen Pet)
There are a number of constituencies where a 10% drop in the Labour vote to the BNP would let in the Lib Dems or the Tories as the second placed party. This could lead to a significant fall in the Labour seats held by the 'seat predictors'.