ITV News Election Analyst Professor Colin Rallings has said Ukip's breakthrough is the "most significant trend in politics for 30 years."
He said: "I remember back in the early 1980s it was the Social Democratic Party, a break away group from Labour, did well in the elections and in the polls.
"They soon joined up with the Liberal Democrats so we became three parties again.
"But now we have a four party situation and in that respect Mr Farage is absolutely right. It makes thing very uncertain as to how the pattern of party loyalties will play out."
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UKIP's successes in the local elections have raised the possibility of them winning a Westminster seat at the general election.
A year ahead of the general election, Ed Miliband's party is seeing only patchy support in areas it should expect to gain ground.
UKIP are likely to make Rotherham a key target for 2015 after a storming result in the local elections.