The Tories could wrestle control from Labour in Brighton and Hove for the first time in 12 years.

An election expert has predicted a political shift in May's city council elections because of general disillusionment with Tony Blair's government.

Election guru David Boothroyd said traditional Conservative voters were not likely to change who they vote for, unlike those who had previously voted Labour.

The election analyser from London-based Indigo Public Affairs consultancy said the city's "bohemian" population in central wards such as Queens Park would tend to vote Green.

Meanwhile more affluent outer areas like Goldsmid and Hangleton and Knoll were returning to the Conservatives now they thought the package offered by David Cameron had become more appealing.

He said the city's Green Party was one of the strongest in the country which meant Labour and Liberal Democrat candidates were being squeezed out but it was not popular enough to take overall control of the whole city.

Mr Boothroyd also said voters were more likely to take into account national factors than local issues when casting their vote.

He said: "I don't think the Conservatives are going to make a big comeback in central wards of the city but they have got chances in some of the outer wards.

"People who are doing well at work and are concerned about keeping up the standards of living and have tended to go between Labour and Conservative now seem to be switching to Conservative because they think they have got their act together.

"Then you have got a fairly young, cosmopolitan and bohemian population - people who would have happily voted Labour in the 90s but are now disillusioned - not just because of the war but all sorts of other things to do with civil liberties.

"The Green Party are consolidating a lot of this strength."

Labour has been the dominant party locally since the mid-1980s. It won control of the then Brighton Borough Council in 1986, Hove Borough Council in 1995 and the new unitary authority of Brighton and Hove in 1996.

In 1997 it won all three parliamentary seats and held on to them in the two successive general elections although some have claimed its grip on local power has been slipping ever since.

Mr Boothroyd said the prediction was a mix of statistical analysis and intuition based on 17 years of experience. He said it was an early version which would be revised nearer May and was the result of an examination of figures from previous elections, the weekly lists of by-elections and opinion polls.

Labour council leader Simon Burgess said: "It is a very real possibility that the Conservatives could take control in May.

"People presume Conservatives wouldn't ever win here but if the Labour vote gets split between different parties it could.

"We are working very hard trying to stop this happening but people need to be aware that if they don't want a Conservative council they need to vote Labour."

Green Party leader Keith Taylor agreed his party were likely to get a lot of Labour's votes but whether that would lead to a Conservative or Labour majority remained to be seen.

He said: "What is for sure is neither of them will have an outright majority or overall control."