Why has Britain gotten so xenophobic? Is it because of Eastern Europeans immigrating once the EU expanded in 04, because you never really heard much about groups like UKIP or the BNP gaining any traction in the 90's and much of the 00's.
Well UKIP and BNP have only really seen success in European elections, which only became elected through PR following the 1999 European act, and used for the first time at the '04 elections. Before that, UKIP won 7% and three seats in the '99 Euro's, under FPTP, but then so did the Greens near enough, and the Euro's pathetic turnout now helps minor parties, whereas in the past it didn't make any difference.
Before that, UKIP's precursor the Referendum Party won 2.6%, at the '97 election - not a great deal less than their best of 3.1% they achieved in the last general election. Other than that, you've got several reasons, some of which have already been mentioned:
-Eastern European immigration has been a growing concern for the public, and regularly 'highlighted' by a very right-wing, xenophobic press.
-main two are distinctly less broad-church entities now, meaning their capture of total vote was rapidly on the decline, opening the way for right-of-Tory votes
-the Tories are less inclined to court racists than in the past, even in recent history, as opposition, the Tory leaders who preceded Cameron (especially IDS/Hague) put far more effort into appealing to them than Cameron, and his 'centrist' electioneering did.