I believe that the apparent surge in UKIP popularity is down to the fact that Farage is willing to air/discuss/debate issues, such as unmanaged immigration and EU membership, that the mainstream parties seem determined not to discuss.
During the New Labour years anyone who even raised the issue of immigration was immediately branded a racist and stamped upon by the politically correct lefties, yet it was undoubtedly a subject that 'the man in the pub' held strong views on. Someone who has 'decriminalised' the debate is bound to pick up some support.