South West Norfolk is the biggest constituency in East Anglia and measures more than 500 square miles, making it the 36th largest in the whole of the UK.

More than a fifth of the 100,000 population live in Thetford and apart from the other towns of Swaffham and Downham Market, the vast majority of the rest of the electorate live in villages which stretch from Walpole Highway in the north west to Garboldisham in the south east.

The constituency is the most sparsely populated in the region with a density of 0.8 people per hectare, so whoever wins the seat after May 7 will have certainly earned it in terms of pounding the beat across the patch.

The breadth of the patch is mirrored in the diversity of residents and the issues which will be raised on the doorsteps during the campaign.

Major housing developments remain major talking points in Thetford and Downham Market with debate centred on the ability of local services such as schools, GP surgeries and roads to cope with the influx of more people.

Thetford has seen massive investment around the town, with more money on the way for the major Riverside development.

After decades of campaigning, the A11 dualling from Thetford to Barton Mills has finally been completed, giving a major boost to links to the constituency.

The other significant investment in South West Norfolk has been the £300m to RAF Marham ahead of arrival of the F-35 jets.

An interesting issue in the campaign will be whether Conservative Elizabeth Truss – who won the seat in 2010 – will benefit from the positive windfalls or be punished by voters for the controversial growth in some parts of the area.

South West Norfolk has an interesting age profile. According to Office for National Statistics figures, the constituency has an average age of 37 (compared with a UK-wide figure of 39) but the percentage of over 65s is 22.4% (national figure is 17%),

Manual work – especially in factories and on the fields – makes up a significant percentage of employment in the area and contributes to the fact that the average wage is £477 per week, well down on the national figure of £528. Just 1% of the population claims Job Seekers' Allowance and 12% work in the public sector (19%). Three in 10 work in retail and manufacturing.

The percentage of people born outside the UK is 10% (13%) and the number of people with a degree or higher qualification is 18% (27%).

Those figures will be key in one of the area's most controversial issues – immigration.

In Thetford, migrants are thought to make up almost a fifth of the population, with many missed by the census.

When it comes to health, 79% of people said their health was very good or good. (81%).

The average house price in South West Norfolk is £154,000 (£210,000) and two thirds of houses are owner-occupied.

Conservatives have held the South West Norfolk seat since 1964.

The majority in 2010 was 13,140 and the seat has been held comfortably since 1974, apart from in 1997 – when Labour won nationally by a landslide – and Gillian Shephard came within 2400 votes of losing the seat.

There were fascinating close battles with a Labour majorities of just 53, 260, 193 and 78 in 1945, 1950, 1955 and 1959 and a Conservative majority of just 442, 123, 775 and 380 in 1951, 1964, 1966

To oust Ms Truss, Labour would need a swing of 15% and the Liberal Democrats would require a 13% swing.

Voter turnout in 2010 in South West Norfolk was 67% (UK average 65).

The bookies have Ms Truss as 1-50 to retain her seat with UKIP at 10/1, Labour at 50/1 and the Lib Dems and Greens at 100/1.

The local council seats in the constituency are largely blue dominated but the Nar Valley ward on Breckland and the Watlington ward on King's Lynn and West Norfolk Borough Council are now held by UKIP.

The constituency's election count will take place in King's Lynn, at Lynnsport, alongside the count for North West Norfolk.