The target seats

Every general election has its bellwether constituencies. Rob Sharp takes a tour

Basildon South and Thurrock East
Basildon is the home of the mythical "Essex man" or "white van man" – a term coined by political commentators to describe a particular variety of aspirational, white, skilled, working class, council-house-dwelling tabloid reader who was won over by Margaret Thatcher's promise of social mobility in 1979 but who deserted the Tories in favour of New Labour in 1997. Since the party's re-election in 2001 he has shifted away from Labour because he feels that his key concerns – unemployment, social housing, immigration – are not being addressed. Labour's support may also be undermined by the redrawing of the constituency's boundaries to exclude central Basildon. A planned deep-sea container port will also be an important local issue.

Birmingham Edgbaston
With its leafy, affluent, middle-class suburbs, this seat was Tory for most of its history until the 1997 Labour landslide. It is essentially a microcosm of middle England; a defeat for the sitting MP, Gisela Stuart, would probably signal Gordon Brown's departure from Downing Street. Undecided voters may opt for whichever of the parties is better for their pockets, and the Tory candidate, Deirdre Alden, is keen to emphasise the local relevance of her party's inheritance tax policy. The constituency contains the main campus of University of Birmingham, so Labour's proposed higher education budget cuts will prove unpopular. However, council estates in some wards may shore up the Labour vote.

Brighton Pavilion
A bohemian, progressive, central area surrounded by more conventional suburbs may see the Green leader, Caroline Lucas, win her party's first seat at Westminster. She offers an appealing record to liberals – one untainted by Iraq, identity cards and worsening societal inequality – as well as locally popular environmental credentials. Labour's candidate, Nancy Platts, on the other hand, comes from an Old Labour union background and distances herself from Gordon Brown. Charlotte Vere, the Tory hopeful, has joined the party during David Cameron's leadership and hopes to support failing local businesses.

Buckingham
By convention the Speaker is elected unopposed, and John Bercow, the MP of this solidly Tory constituency, will not face a Labour or a Liberal Democrat challenger. Buckingham contains a smattering of affluent villages that helped him enjoy his party's biggest majority at the last election. But he may face competition from the former UKIP leader Nigel Farage, who will be hoping to capitalise on disillusionment over Bercow's role in last year's expenses scandal – for four years he submitted the highest expenses claim of any Westminster MP – and on the Speaker's dwindling Tory support.

Edinburgh South West
A Conservative seat through the 1980s and most of the 1990s, Edinburgh South West fell to Labour in 1997. It is currently the seat of the Chancellor, Alistair Darling, and therefore has tactical importance. Both parties have suffered here from the increasing popularity of the Liberal Democrats over the last three terms. Voters may back away from a Tory challenge to Darling after it emerged that the "non-dom" Tory party donor Lord Ashcroft financed the party's 2005 candidate, Gordon Buchan. But given the area's mixture of urban, suburban and rural areas, Darling may lose votes to the Scottish National Party candidate, Kaukab Stewart.

Islington South & Finsbury
This North London constituency is often labelled as a stamping ground for the liberal intelligentsia – it was the pre-Downing-Street home of Tony Blair – but it also contains cash-strapped enclaves. Unsurprisingly it was a New Labour stronghold throughout the late 1990s. But with an electorate disillusioned with war in the Middle East, Trident and ID cards, the sitting Labour MP, Emily Thornberry, might have trouble beating the Liberal Democrat hopeful, Bridget Fox, this year. In 2005 the Labour lead was less than two percentage points. Fox's campaign will not be aided, however, by the presence of an unpopular Liberal Democrat administration at Islington Town Hall.

Luton South
Luton has a long history of manufacturing, so the threatened closure of its Vauxhall car plant will be a political campaigning point, along with crime and benefits for the elderly. The 2001 census revealed that a quarter of its population is non-white, and it has a large Muslim population, so religious factors (for example a candidate's views on abortion) may be important. The constituency is normally considered a Labour stronghold, but Margaret Moran, the party's incumbent MP, will stand down after being "outed" last year for spending £22,500 of taxpayers' money treating dry rot. Her replacement, Gavin Shuker, could do well as independents – including Esther Rantzen – may split the vote.

Manchester Withington
Centred on the fashionable Didsbury district, this rich residential area of South Manchester was traditionally a safe Conservative seat. In the 1980s many of its newly wealthy residents moved to Cheshire and converted their original houses into student-style accommodation for academics and young professionals. As a result Labour won the seat in 1987, and by 2001 the party had a five-figure majority. But in the last election the Liberal Democrat candidate, John Leech, won a surprise victory, capitalising on his party's strong presence in local government, disillusionment over Iraq and fears over the closure of the local hospital. Voting may well be influenced more by ideology than, for example, by direct gains through income support.

Milton Keynes South
This middle-class seat, which contains the former code-breaking site at Bletchley Park, was held by the Tory right-winger Barry Legg until 1997, when it was taken by Labour. Since then Labour has been steadily losing ground. With 80,000 voters, Milton Keynes South is one of the country's most populous constituencies. The Labour MP, Phyllis Starkey, claims the important issues locally are house-building, policing and public services (though her party arguably has a patchy record in these areas). The Tories' support for fox-hunting – as well as the party's funding by Lord Ashcroft – has caused controversy in the local press.

York Outer
This is a new seat encircling the city, consisting of its suburbs, the surrounding villages and the University of York's campus. The election is predicted to be a closely fought battle between the Tories and the Liberal Democrats, though the latter control every council within the constituency. The Liberal Democrat candidate, Madeleine Kirk, is clearly targeting the student vote, pledging to oppose future increases in tuition fees, criticising university funding cuts and pledging cash for local schools. The constituency has an above-average number of pensioners, so issues like heating benefit could be important, as could housing and public services. The Liberal Democrats could also benefit from tactical voting against the Tories.