More people in Brighton and Hove voted Green than Labour in the European elections.

It put the Green Party in second place behind the Conservatives.

Caroline Lucas, the Green Party's sole MEP for the giant South-East region, was only just re-elected despite the inroads.

Conservatives came top in every Sussex district, resisting a strong Euro-sceptic challenge from the United Kingdom Independence Party (UKIP).

The Lib Dems struggled to make an impact, squeezed by a combination of high turnout of Conservative voters and a strong protest vote.

Wealden MP Charles Hendry, the Tories' deputy chairman, said: "UKIP did perform well but we were well on top.

"I think we have a lot to take encouragement from. It shows the Government would be mad to sign up to a European constitution.

"That comes through very strongly and the Government will ignore it at their peril. When you think they have all three (parliamentary) seats in Brighton and Hove and they came third, they must be pretty shaken by that."

Dr Paul Taggart, senior politics lecturer at the University of Sussex, warned about reading too much into the European election results, traditionally used by voters to punish whichever party is in office at home.

He said: "People who vote in this election in a way know they can make a mark. Then they go back to their home base."

UKIP's support runs the gamut from deep Euro-scepticism to unease about the European project and difficult-to-understand Euro institutions.

Opinion polls routinely show only about five per cent of the electorate is made up of hardcore Eurosceptics, far lower than the 16 per cent share of the national vote captured by UKIP.

Dr Taggart compared UKIP's success to the Green Party in the 1989 European elections, when the latter captured a 15 per cent share of the vote.

He said: "They had a spectacular success in one election and that is pretty difficult to maintain for these sort of parties."

In Brighton and Hove, however, surging Green Party support may spell trouble for Labour in the general election.

Dr Taggart said: "I think the Green vote in Brighton is very untypical of other cities of a similar size, and the Greens know that.

"They have shown they are a strong force and they are the alternative to Labour. This is not typical of Sussex."

There are ten MEPs representing the South-East: Richard Ashworth (Con); Niranjan Deva (Con); James Elles (Con); Nigel Farage (UKIP); Daniel Hannan (Con); Chris Huhne (LibDem); Caroline Lucas (Greens); Ashley Mote (UKIP); Emma Nicholson (Lib Dem); and Peter Skinner (Lab).