Prime Minister Gordon Brown's Labour party faces another potentially humiliating setback in a parliamentary election in the historic railway town of Crewe next week.

Thursday's contest in the Labour-held constituency, 240 kilometres northwest of London, has taken on a significance outweighing its possible damage to Mr Brown's 67-member majority in the House of Commons.

The campaign is attracting intense national media coverage with the opposition Conservatives trying to extend their wave of success and achieve their first by-election gain for 26 years.

Defeat in Crewe would further undermine Mr Brown's position, already weakened by sliding poll ratings and a self-inflicted row over a tax change that hurt the poorest.

The battleground combines the affluent market town of Nantwich and its working class neighbour Crewe, once dominated by the railway industry and still a major rail junction.

Supermarkets and housing developments stand where thousands of steam engines were built for the Victorian rail network.

Just 650 people work at the remaining railway factory that at one time employed 20,000.

The seat was held for 34 years by popular Labour traditionalist Gwyneth Dunwoody, who died aged 77 last month.

Her 49-year-old daughter Tamsin, described by party activists as "chip off the same block", is fighting to defend the 7,000-vote majority and regain the seat for Labour.

But she will have to work hard to convert voters' sympathy for her mother's death into Labour votes.

On a walkabout through the upscale food and gift stalls of Nantwich's Market Hall, Ms Dunwoody was greeted by a sales assistant who remembered her mother's visits to buy cakes.

"I just loved your mum, she was lovely," she told Ms Dunwoody, before confiding later that she would be voting Conservative.

Labour, still reeling from a rout in local elections earlier this month, has launched an aggressive campaign.

It has portrayed the 34-year-old Conservative candidate Edward Timpson as an upper-class "toff", with activists dressed in top hats and tail coats dogging his campaign appearances.

Mr Timpson's family run a chain of key, lock and shoe repair stores and he lives in what Ms Dunwoody describes as a £1.5 million "mansion" in the countryside outside Crewe.