It isn't a phenomenon that is restricted to England, unfortunately.
In Norway, there is a 'Progressive Party', that wean quite a lot of (especially) the older voters away from their Labour roots, by promising everything Labour does not, while accentuating already held fears that their heritage and culture is under attack.

It is National Socialism, and it is rampant in Europe.
They are small parties (although the Norwegian one came 3rd in the recent County Council elections... and the word is that they could also lead the next Government), but with their ordinary 'policies' not that far removed from centre-left thinking, it affords them the platform to be able to point the blame for among other things, the rising crime rates, at the uncivilised outsider.

These politicians do not speak with the equivalent of an Eastenders accent. Nor do they support Millwall. They have honed their patter to make what they're saying seem almost plausible.
Were the BNP to develop that kind of finesse, one could have a lot of confused and undecided people out there.

B.