Spelthorne is a constituency^{[n 1]} in Surrey represented in the House of Commons of the UK Parliament since 2010 by Kwasi Kwarteng, a Conservative, who served as Chancellor of the Exchequer for 38 days in September and October 2022.^{[n 2]}

1918–1945: The Urban Districts of Feltham, Hampton, Hampton Wick, Staines, Sunbury-on-Thames, and Teddington, and the Rural District of Staines.

1945–1950: The Urban Districts of Feltham, Staines, Sunbury-on-Thames, and Yiewsley and West Drayton.

1950–1955: The Urban Districts of Feltham, Staines, and Sunbury-on-Thames.

1955–1983: The Urban Districts of Staines and Sunbury-on-Thames.

1983–present: The Borough of Spelthorne (same content as above)

Spelthorne was one of six hundreds of the historic county of Middlesex which covered its south west. It had thirteen historic parishes whereas the modern borough and seat has seven. The London Government Act 1963 placed the historic county in London except for two areas, one being the seven south-westernmost parishes of Spelthorne and Middlesex, placed since the commencement of the Act in April 1965 in Surrey.

From 1885 to 1918 it was in the inceptive Uxbridge seat, before which its electorate contributed to the two-seat Middlesex constituency since the 13th century creation of the House of Commons of England.

The seat is south of Heathrow Airport bounded by a long meander of the Thames. It is a more built-up area with numerous but less expansive green spaces, fewer private roads and little woodland compared to further south in Surrey. Some 30% is embanked reservoir or low-lying flood plain therefore immune against building.^[4] Contrasting with these large areas of fresh water, Surrey County Council have built a waste incinerator in Charlton in the seat and the 1970s saw the construction of the M3 and M25 motorways through the seat, the latter along its western border.

While relative to the county as a whole this borough is marginally less affluent, in national terms it is more affluent. Workless claimants (registered jobseekers) were in November 2012 significantly lower than the national average of 3.8%, at 2.0% of the population based on a statistical compilation by The Guardian,^[5] only 0.3% higher than the affluent neighbouring constituency of Twickenham in London. Most residents can afford to buy their own homes: social housing accounts for only 10% of the total,^[6] and the proportion of professionals and managerial workers is high. Spelthorne has Labour's highest vote share of the eleven seats (30.5%) in the modern reduced definition of Surrey, where Stanwell is as at 2024 the only County Council division (seat) held by a Labour councillor. Stanwell in common with Sunbury Common has significant social housing.

Spelthorne exceeds the average quota of commercial property of Surrey's seats — it contains about 20% of the county's commercial/industrial property, including large plants or wholesale units of Complete Cover Group, Kingston Technology, Edmundson Electrical, Esso Petroleum, Johnson & Johnson Vision Products, Thames Water, Shepperton Film Studios, wholesalers and storage companies. Major offices/creative facilities of BP (its global HQ), Del Monte, NatWest, Samsung, Richmond Film Services and film/television ancillary businesses are in the constituency.

During the 2016 referendum on the UK's EU membership, the majority of voters in the area voted in favour of exiting the European Union.^[7] This was the preferred outcome of Spelthorne MP Kwasi Kwarteng.^[8]

The 1918 to 1945 broadest, initial version of the parliamentary division saw no marginal majorities and can be squarely analysed as a Conservative safe seat based on length of party tenure and size of majorities.

In the 1945 general election George Pargiter (Lab) was elected in the Attlee Ministry landslide while the boundaries of the seat saw a favourable form to the party during expansion of London when the area extended to areas to the north, including Feltham and Bedfont (removed in 1955 — see Feltham and Heston) and had cast off Hampton, Hampton Wick and Teddington, before 1945 part of the seat.

Since the 1955 boundary reduction and a local emphasis or demand upon private housing relative to social housing, the reduced area has eight Conservative candidate majorities of greater than 11% and three lower majorities: 1966, 1997 and 2001. The earliest of these produced the narrowest margin of victory, 5% of the vote. Based on length of party tenure and majorities the seat would be considered safe by most UK electoral analysts including of academic standing.

The constituency's first MP was Philip Pilditch, an architect who piloted the Ancient Monuments Act 1931 through Parliament: see Scheduled Monument. The MP for Spelthorne since 2010 is the former Chancellor Kwasi Kwarteng.

• List of parliamentary constituencies in Surrey