I can say this is primarily due to the rise of UKIP (where you cannot even become a member of UKIP if you ever were a member of the British National Party, among other parties and groups) as a legitimate anti-EU libertarian-leaning sovereignty party.

So raise up a sweet tea in salute (The Brits might say, Hear!  Hear!) of UKIP that has now driven the BNP out of British politics.  I doubt the left will offer that toast.  But I do!