# South Northamptonshire (UK Parliament constituency)

South Northamptonshire is a constituency represented in the House of Commons of the UK Parliament since 2024 by Sarah Bool. As with all constituencies, the constituency elects one Member of Parliament (MP) by the first past the post system of election at least every five years.

## Constituency profile

This is a rural seat around Towcester and Brackley. There is a significant motorsport sector including the north half of Silverstone Circuit. Incomes and house prices are above average for the UK.

## History

Before 2010, the constituency existed from 1832 to 1918, and from 1950 to 1974, however on different boundaries during each period. It elected two Members of Parliament (MPs) by the bloc vote system of election from 1832, until the representation was reduced in 1885 to one member elected by the first past the post system.

### Prominent members

Three names feature prominently among the area's Commons members, the 3rd and 5th Earl Spencer (during their tenures as MP having a courtesy title only, Viscount Althorp – Althorp is a major country house in the seat, well known as the childhood home of Diana, Princess of Wales); Edward Fitzroy (son of Lord Southampton), Speaker of the House of Commons from 1928 until his death in 1943; and lastly, Reginald Manningham-Buller, 1st Viscount Dilhorne who on accomplishment of a peerage sat for the final two years of his life as the historic equivalent of the President of the Supreme Court of the United Kingdom with additional functions, the Lord Chancellor.
In the 19th century history of the seat the Cartwright family (with three members) lived in the stately home Aynhoe Park near Banbury.

### History of boundaries

The seat was abolished in 1918 to form the new constituency of Daventry, then recreated in 1950 caused by a relatively short-lived abolition of Daventry. In 1974 the constituency was almost wholly swallowed up by a reborn Daventry, which on wide boundaries saw substantial population growth.
This called for recreation in 2010 whereby most of the electoral wards were taken from the former version of the Daventry seat.

### Present bordering constituencies

The constituency is bordered by Daventry and Northampton South to the north, Wellingborough to the north east, Milton Keynes North and Milton Keynes South to the south east, Buckingham to the south, Banbury to the south west and Kenilworth and Southam to the west.

## Boundaries
### Historic

1832–1885: The Hundreds of Kings Sutton, Chipping Warden, Greens Norton, Cleley, Towcester, Fawsley, Wymersley, Spelhoe, Nobottle Grove, and Guilsborough.
1885–1918: The Sessional Divisions of Brackley and Towcester, and part of the Sessional Division of Daventry. (The part of the Sessional Division of Daventry included in South Northamptonshire excluded the parishes of Ashby St. Ledgers, Barby, Claycoton Crick, Elkington, Kilsby, Lilboume, Long Buckley, Stanford, Watford, West Haddon, Winwick, and Yelvertoft, which were assigned to Mid Northamptonshire).
1950–1974: The Boroughs of Daventry and Brackley, and the Rural Districts of Brackley, Daventry, Northampton, and Towcester.
2010–2021: The District of South Northamptonshire wards of Astwell, Blakesley, Blisworth, Brackley East, Brackley South, Brackley West, Chase, Cogenhoe, Collingtree, Cosgrove, Courteenhall, Deanshanger, Grafton, Kings Sutton, Kingthorn, Little Brook, Middleton Cheney, Salcey, Silverstone, Steane, Tove, Towcester Brook, Towcester Mill, Wardoun, Washington, Whittlewood, and Yardley, and the Borough of Northampton wards of East Hunsbury, Nene Valley, and West Hunsbury.
2021–2024: With effect from 1 April 2021, the Borough of Northampton and the District of South Northamptonshire were abolished and absorbed into the new unitary authority of West Northamptonshire. From that date, the constituency comprised the District of West Northamptonshire wards of Brackley, Bugbrooke (part), Deanshanger, Duston West and St. Crispin (part), East Hunsbury and Shelfleys, Hackleton and Grange Park, Middleton Cheney, Nene Valley, Silverstone, Sixfields (part), and Towcester and Roade.

### Current

Further to the 2023 review of Westminster constituencies, which came into effect for the 2024 general election, the composition of the constituency is as follows (as they existed on 1 April 2021):
* The District of North Northamptonshire ward of Irchester (polling districts WAA, WAB, WPA, WPB and WPC)
* The District of West Northamptonshire wards of Brackley; Bugbrooke; Deanshanger; Hackleton and Grange Park; Middleton Cheney; Silverstone (polling districts SAA, SAB, SAN, SAT, SBP, SBX, SCV, SDG, SDW, SDZ, SEF, SEW, SFE, SFF, SFN, SFO, SFR, SFW, SGD, SGF and SGK); Towcester and Roade.
The parts in the former Borough of Northampton were transferred to Northampton South. The constituency gained the part of the Irchester ward from Wellingborough and the remainder of the Bugbrooke ward from Daventry. A small part of Silverstone ward was transferred to Daventry.

## Members of Parliament
### MPs 1832–1885

Northamptonshire prior to 1832
| Election | First member | First member | First party | Second member | Second member | Second party |
| 1832 | | Viscount Althorp | Whig | | William Ralph Cartwright | Tory |
| 1834 | | Viscount Althorp | Whig | | William Ralph Cartwright | Conservative |
| 1835 | | Sir Charles Knightley, Bt | Conservative | | William Ralph Cartwright | Conservative |
| 1846 by-election | | Sir Charles Knightley, Bt | Conservative | | Cpt. Richard Howard-Vyse | Conservative |
| 1852 | | Rainald Knightley | Conservative | | Cpt. Richard Howard-Vyse | Conservative |
| 1857 | | Rainald Knightley | Conservative | | Viscount Althorp | Whig |
| 1858 by-election | | Rainald Knightley | Conservative | | Col. Henry Cartwright | Conservative |
| 1868 | | Rainald Knightley | Conservative | | Fairfax Cartwright | Conservative |
| 1881 by-election | | Rainald Knightley | Conservative | | Pickering Phipps | Conservative |
| 1885 | Redistribution of Seats Act: reduced to one member | Redistribution of Seats Act: reduced to one member | Redistribution of Seats Act: reduced to one member | Redistribution of Seats Act: reduced to one member | Redistribution of Seats Act: reduced to one member | Redistribution of Seats Act: reduced to one member |

### MPs 1885–1918

| Year | Member | Party |
| 1885 | Sir Rainald Knightley | Conservative |
| 1892 | David Guthrie | Liberal |
| 1895 | Hon. Edward Douglas-Pennant | Conservative |
| 1900 | Hon. Edward FitzRoy | Conservative |
| 1906 | Archibald Grove | Liberal |
| 1910 | Hon. Edward FitzRoy | Conservative |
| 1917 | Hon. Edward FitzRoy | National Party |
| 1918 | Hon. Edward FitzRoy | Unionist |
| 1918 | Constituency abolished, but revived in 1950 | Constituency abolished, but revived in 1950 |

### MPs 1950–1974

Daventry and Kettering prior to 1950
| Election | Member | Party | Notes |
| 1950 | Reginald Manningham-Buller | Conservative | Resigned 1962 on being raised to the peerage |
| 1962 by-election | Arthur Jones | Conservative |
| February 1974 | Constituency abolished, but revived in 2010 | Constituency abolished, but revived in 2010 |

### MPs since 2010

Daventry prior to 2010
| Election | Election | Member | Party |
| | 2010 | Andrea Leadsom | Conservative |
| | 2024 | Sarah Bool | Conservative |

## Elections
### Elections in the 2020s

General election 2024: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Sarah Bool | 19,191 | 35.7 | −27.5 |
| | Labour | Rufia Ashraf | 15,504 | 28.9 | +8.1 |
| | Reform UK | Paul Hogan | 8,962 | 16.7 | New |
| | Liberal Democrats | Stewart Tolley | 4,989 | 9.3 | −1.8 |
| | Green | Emmie Williamson | 3,040 | 5.7 | +1.9 |
| | Independent | Ian McCord | 1,556 | 2.9 | New |
| | Workers Party | Mick Stott | 246 | 0.5 | New |
| | Independent | Stuart Robert | 209 | 0.4 | New |
| Majority | Majority | Majority | 3,687 | 6.8 | −35.6 |
| Turnout | Turnout | Turnout | 53,697 | 68.6 | −4.3 |
| Registered electors | Registered electors | Registered electors | 78,233 | | |
| | Conservative hold | Conservative hold | Swing | −17.8 | |

### Elections in the 2010s

General election 2019: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Andrea Leadsom | 41,755 | 62.4 | −0.1 |
| | Labour | Gen Kitchen | 13,994 | 20.9 | −6.4 |
| | Liberal Democrats | Chris Lofts | 7,891 | 11.8 | +6.2 |
| | Green | Denise Donaldson | 2,634 | 3.9 | +1.8 |
| | Independent | Josh Phillips | 463 | 0.7 | +0.2 |
| | Independent | Stuart McCutcheon | 171 | 0.3 | New |
| Majority | Majority | Majority | 27,761 | 41.5 | +6.3 |
| Turnout | Turnout | Turnout | 66,908 | 73.7 | −2.2 |
| | Conservative hold | Conservative hold | Swing | +3.15 | |
General election 2017: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Andrea Leadsom | 40,599 | 62.5 | +2.4 |
| | Labour | Sophie Johnson | 17,759 | 27.3 | +10.6 |
| | Liberal Democrats | Chris Lofts | 3,623 | 5.6 | −0.3 |
| | UKIP | Nigel Wickens | 1,363 | 2.1 | −11.4 |
| | Green | Denise Donaldson | 1,357 | 2.1 | −1.6 |
| | Independent | Josh Philips | 297 | 0.5 | New |
| Majority | Majority | Majority | 22,840 | 35.2 | −8.2 |
| Turnout | Turnout | Turnout | 64,998 | 75.9 | +4.8 |
| | Conservative hold | Conservative hold | Swing | −4.15 | |
General election 2015: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Andrea Leadsom | 36,607 | 60.1 | +4.9 |
| | Labour | Lucy Mills | 10,191 | 16.7 | −0.6 |
| | UKIP | Roger Clark | 8,204 | 13.5 | +9.5 |
| | Liberal Democrats | Tom Snowdon | 3,613 | 5.9 | −15.1 |
| | Green | Damon Boughen | 2,247 | 3.7 | +2.6 |
| Majority | Majority | Majority | 26,416 | 43.4 | +9.2 |
| Turnout | Turnout | Turnout | 60,862 | 71.1 | −1.9 |
| | Conservative hold | Conservative hold | Swing | +2.75 | |
General election 2010: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Andrea Leadsom | 33,081 | 55.2 | +3.7 |
| | Liberal Democrats | Scott Collins | 12,603 | 21.0 | +3.9 |
| | Labour | Matthew May | 10,380 | 17.3 | −11.4 |
| | UKIP | Barry Mahoney | 2,406 | 4.0 | +1.4 |
| | English Democrat | Tony Tappy | 735 | 1.2 | New |
| | Green | Marcus Rock | 685 | 1.1 | New |
| Majority | Majority | Majority | 20,478 | 34.2 | |
| Turnout | Turnout | Turnout | 59,890 | 73.0 | |
| | Conservative hold | Conservative hold | Swing | +3.8 | |

### Elections in the 1970s

General election 1970: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Arthur Jones | 29,070 | 51.16 | |
| | Labour | Gordon Roberts | 21,131 | 37.18 | |
| | Liberal | Peter Smout | 6,626 | 11.66 | New |
| Majority | Majority | Majority | 7,939 | 13.98 | |
| Turnout | Turnout | Turnout | 56,827 | 77.87 | |
| | Conservative hold | Conservative hold | Swing | | |

### Elections in the 1960s

General election 1966: South Northamptonshire :
| Party | Party | Candidate | Votes | % |
| | Conservative | Arthur Jones | 25,023 | 52.84 |
| | Labour | Graham Ridge | 22,332 | 47.16 |
| Majority | Majority | Majority | 2,691 | 5.68 |
| Turnout | Turnout | Turnout | 47,355 | 82.18 |
| | Conservative hold | Conservative hold | Swing | |
General election 1964: South Northamptonshire :
| Party | Party | Candidate | Votes | % |
| | Conservative | Arthur Jones | 24,823 | 54.27 |
| | Labour | Ivor Wilde | 20,916 | 45.73 |
| Majority | Majority | Majority | 3,907 | 8.54 |
| Turnout | Turnout | Turnout | 45,739 | 83.04 |
| | Conservative hold | Conservative hold | Swing | |
1962 South Northamptonshire by-election :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Arthur Jones | 14,921 | 41.15 | −15.83 |
| | Labour | Ivor Wilde | 14,004 | 38.62 | −4.40 |
| | Liberal | N. Picarda | 7,002 | 19.31 | New |
| | Independent | P. Buchan | 332 | 0.9 | New |
| Majority | Majority | Majority | 917 | 2.53 | −11.43 |
| Turnout | Turnout | Turnout | 36,259 | | |
| | Conservative hold | Conservative hold | Swing | | |

### Elections in the 1950s

General election 1959: South Northamptonshire :
| Party | Party | Candidate | Votes | % |
| | Conservative | Reginald Manningham-Buller | 24,226 | 56.98 |
| | Labour | Arthur Richardson | 18,292 | 43.02 |
| Majority | Majority | Majority | 5,934 | 13.96 |
| Turnout | Turnout | Turnout | 42,518 | 82.72 |
| | Conservative hold | Conservative hold | Swing | |
General election 1955: South Northamptonshire :
| Party | Party | Candidate | Votes | % |
| | Conservative | Reginald Manningham-Buller | 21,497 | 55.35 |
| | Labour | Ronald Lewis | 17,339 | 44.65 |
| Majority | Majority | Majority | 4,158 | 10.70 |
| Turnout | Turnout | Turnout | 38,836 | 81.56 |
| | Conservative hold | Conservative hold | Swing | |
General election 1951: South Northamptonshire :
| Party | Party | Candidate | Votes | % |
| | Conservative | Reginald Manningham-Buller | 21,282 | 53.59 |
| | Labour | Dennis Webb | 18,434 | 46.41 |
| Majority | Majority | Majority | 2,848 | 7.18 |
| Turnout | Turnout | Turnout | 39,716 | 85.90 |
| | Conservative hold | Conservative hold | Swing | |
General election 1950: South Northamptonshire :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Reginald Manningham-Buller | 18,612 | 47.62 | |
| | Labour | Dennis Webb | 16,852 | 43.12 | |
| | Liberal | Llewellyn Evans | 3,620 | 9.26 | |
| Majority | Majority | Majority | 1,760 | 4.50 | |
| Turnout | Turnout | Turnout | 39,084 | 87.10 | |
| | Conservative win (new seat) | Conservative win (new seat) | Conservative win (new seat) | Conservative win (new seat) | Conservative win (new seat) |

## Election results 1868–1918
### Elections in the 1860s

General election 1868: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Rainald Knightley | 2,522 | 34.4 | −0.3 |
| | Conservative | Fairfax Cartwright | 2,505 | 34.2 | +1.3 |
| | Liberal | Frederick John FitzRoy | 2,305 | 31.4 | −0.9 |
| Majority | Majority | Majority | 200 | 2.8 | +2.2 |
| Turnout | Turnout | Turnout | 4,819 (est) | 76.0 (est) | −3.4 |
| Registered electors | Registered electors | Registered electors | 6,338 | | |
| | Conservative hold | Conservative hold | Swing | +0.1 | |
| | Conservative hold | Conservative hold | Swing | +0.9 | |

### Elections in the 1870s

General election 1874: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Fairfax Cartwright | Unopposed | Unopposed | Unopposed |
| | Conservative | Rainald Knightley | Unopposed | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 6,029 | | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |

### Elections in the 1880s

General election 1880: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Fairfax Cartwright | Unopposed | Unopposed | Unopposed |
| | Conservative | Rainald Knightley | Unopposed | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 6,093 | | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
Cartwright's death caused a by-election.
By-election, 15 Feb 1881: Northamptonshire South (1 seat) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Pickering Phipps | Unopposed | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 6,093 | | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
General election 1885: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Rainald Knightley | 4,074 | 50.4 | N/A |
| | Liberal | Maurice Fitzgerald | 4,012 | 49.6 | New |
| Majority | Majority | Majority | 62 | 0.8 | N/A |
| Turnout | Turnout | Turnout | 8,086 | 83.9 | N/A |
| Registered electors | Registered electors | Registered electors | 9,636 | | |
| | Conservative hold | Conservative hold | Swing | N/A | |
General election 1886: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Rainald Knightley | 4,003 | 52.1 | +1.7 |
| | Liberal | James Carmichael | 3,687 | 47.9 | −1.7 |
| Majority | Majority | Majority | 316 | 4.2 | +3.4 |
| Turnout | Turnout | Turnout | 7,690 | 79.8 | −4.1 |
| Registered electors | Registered electors | Registered electors | 9,636 | | |
| | Conservative hold | Conservative hold | Swing | +1.7 | |

### Elections in the 1890s

General election 1892: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Liberal | David Guthrie | 3,930 | 50.3 | +2.4 |
| | Conservative | Thomas Leslie-Melville-Cartwright | 3,882 | 49.7 | −2.4 |
| Majority | Majority | Majority | 48 | 0.6 | N/A |
| Turnout | Turnout | Turnout | 7,812 | 84.4 | +4.6 |
| Registered electors | Registered electors | Registered electors | 9,251 | | |
| | Liberal gain from Conservative | Liberal gain from Conservative | Swing | +2.4 | |
General election 1895: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Edward Douglas-Pennant | 4,553 | 57.8 | +8.1 |
| | Liberal | David Guthrie | 3,324 | 42.2 | −8.1 |
| Majority | Majority | Majority | 1,229 | 15.6 | N/A |
| Turnout | Turnout | Turnout | 7,877 | 86.2 | +1.8 |
| Registered electors | Registered electors | Registered electors | 9,134 | | |
| | Conservative gain from Liberal | Conservative gain from Liberal | Swing | +8.1 | |

### Elections in the 1900s

General election 1900: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Edward FitzRoy | 4,174 | 56.9 | −0.9 |
| | Liberal | Archibald Grove | 3,166 | 43.1 | +0.9 |
| Majority | Majority | Majority | 1,008 | 13.8 | −1.8 |
| Turnout | Turnout | Turnout | 7,340 | 81.8 | −4.4 |
| Registered electors | Registered electors | Registered electors | 8,976 | | |
| | Conservative hold | Conservative hold | Swing | −0.9 | |
General election 1906: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Liberal | Archibald Grove | 4,136 | 52.0 | +8.9 |
| | Conservative | Charles Douglas-Pennant | 3,814 | 48.0 | −8.9 |
| Majority | Majority | Majority | 322 | 4.0 | N/A |
| Turnout | Turnout | Turnout | 7,950 | 88.1 | +6.3 |
| Registered electors | Registered electors | Registered electors | 9,023 | | |
| | Liberal gain from Conservative | Liberal gain from Conservative | Swing | +8.9 | |

### Elections in the 1910s

General election January 1910: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Edward FitzRoy | 4,565 | 53.6 | +5.6 |
| | Liberal | Frederick Kellaway | 3,955 | 46.4 | −5.6 |
| Majority | Majority | Majority | 610 | 7.2 | N/A |
| Turnout | Turnout | Turnout | 8,520 | 91.7 | +3.6 |
| Registered electors | Registered electors | Registered electors | 9,290 | | |
| | Conservative gain from Liberal | Conservative gain from Liberal | Swing | +5.6 | |
General election December 1910: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Edward FitzRoy | 4,340 | 53.1 | −0.5 |
| | Liberal | Arthur Augustus Thomas | 3,827 | 46.9 | +0.5 |
| Majority | Majority | Majority | 513 | 6.2 | −1.0 |
| Turnout | Turnout | Turnout | 8,167 | 87.9 | −3.8 |
| Registered electors | Registered electors | Registered electors | 9,290 | | |
| | Conservative hold | Conservative hold | Swing | −0.5 | |
General Election 1914–15:
Another General Election was required to take place before the end of 1915. The political parties had been making preparations for an election to take place and by July 1914, the following candidates had been selected;
* Unionist: Edward FitzRoy
* Liberal: Arthur Augustus Thomas

## Election results 1832–1868
### Elections in the 1830s

General election 1832: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % |
| | Tory | William Ralph Cartwright | Unopposed | Unopposed |
| | Whig | John Spencer | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 4,425 | |
| | Tory win (new seat) | Tory win (new seat) | Tory win (new seat) | Tory win (new seat) |
| | Whig win (new seat) | Whig win (new seat) | Whig win (new seat) | Whig win (new seat) |
General election 1835: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % |
| | Conservative | William Ralph Cartwright | Unopposed | Unopposed |
| | Conservative | Charles Knightley | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 4,463 | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
| | Conservative gain from Whig | Conservative gain from Whig | Conservative gain from Whig | Conservative gain from Whig |
General election 1837: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % |
| | Conservative | William Ralph Cartwright | Unopposed | Unopposed |
| | Conservative | Charles Knightley | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 4,626 | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold |

### Elections in the 1840s

General election 1841: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | William Ralph Cartwright | 2,436 | 42.8 | N/A |
| | Conservative | Charles Knightley | 2,324 | 40.9 | N/A |
| | Whig | Henry FitzRoy | 925 | 16.3 | New |
| Majority | Majority | Majority | 1,399 | 24.6 | N/A |
| Turnout | Turnout | Turnout | 3,305 (est) | 72.0 (est) | N/A |
| Registered electors | Registered electors | Registered electors | 4,589 | | |
| | Conservative hold | Conservative hold | Swing | N/A | |
| | Conservative hold | Conservative hold | Swing | N/A | |
Cartwright resigned by accepting the office of Steward of the Chiltern Hundreds, causing a by-election.
By-election, 24 February 1846: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Richard Howard-Vyse | Unopposed | Unopposed | Unopposed |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
General election 1847: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Charles Knightley | 2,272 | 39.2 | −1.7 |
| | Conservative | Richard Howard-Vyse | 2,064 | 35.6 | −7.2 |
| | Whig | Anthony Henley | 1,460 | 25.2 | +8.9 |
| Majority | Majority | Majority | 604 | 10.4 | −14.2 |
| Turnout | Turnout | Turnout | 3,628 (est) | 76.7 (est) | +4.7 |
| Registered electors | Registered electors | Registered electors | 4,729 | | |
| | Conservative hold | Conservative hold | Swing | −3.1 | |
| | Conservative hold | Conservative hold | Swing | −5.8 | |

### Elections in the 1850s

General election 1852: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Richard Howard-Vyse | 1,833 | 47.9 | +12.3 |
| | Conservative | Rainald Knightley | 1,833 | 47.9 | +8.7 |
| | Whig | John Houghton | 164 | 4.3 | −20.9 |
| Majority | Majority | Majority | 1,669 | 43.6 | +33.2 |
| Turnout | Turnout | Turnout | 1,997 (est) | 43.7 (est) | −33.0 |
| Registered electors | Registered electors | Registered electors | 4,568 | | |
| | Conservative hold | Conservative hold | Swing | +11.4 | |
| | Conservative hold | Conservative hold | Swing | +9.6 | |
General election 1857: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Whig | John Spencer | 2,107 | 37.4 | +33.1 |
| | Conservative | Rainald Knightley | 1,932 | 34.3 | −13.6 |
| | Conservative | Richard Howard-Vyse | 1,593 | 28.3 | −19.6 |
| Majority | Majority | Majority | 514 | 9.1 | N/A |
| Turnout | Turnout | Turnout | 3,870 (est) | 82.8 (est) | +39.1 |
| Registered electors | Registered electors | Registered electors | 4,675 | | |
| | Whig gain from Conservative | Whig gain from Conservative | Swing | +33.1 | |
| | Conservative hold | Conservative hold | Swing | −15.1 | |
Spencer succeeded to the peerage, becoming 5th Earl Spencer and causing a by-election.
By-election, 20 February 1858: Northamptonshire South :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Henry Cartwright | 1,983 | 51.1 | −11.5 |
| | Whig | Anthony Henley | 1,899 | 48.9 | +11.5 |
| Majority | Majority | Majority | 84 | 2.2 | N/A |
| Turnout | Turnout | Turnout | 3,882 | 83.0 | +0.2 |
| Registered electors | Registered electors | Registered electors | 4,675 | | |
| | Conservative gain from Whig | Conservative gain from Whig | Swing | −11.5 | |
General election 1859: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Rainald Knightley | Unopposed | Unopposed | Unopposed |
| | Conservative | Henry Cartwright | Unopposed | Unopposed | Unopposed |
| Registered electors | Registered electors | Registered electors | 4,955 | | |
| | Conservative hold | Conservative hold | Conservative hold | Conservative hold | Conservative hold |
| | Conservative gain from Liberal | Conservative gain from Liberal | Conservative gain from Liberal | Conservative gain from Liberal | Conservative gain from Liberal |

### Elections in the 1860s

General election 1865: Northamptonshire South (2 seats) :
| Party | Party | Candidate | Votes | % | ±% |
| | Conservative | Rainald Knightley | 2,206 | 34.7 | N/A |
| | Conservative | Henry Cartwright | 2,092 | 32.9 | N/A |
| | Liberal | Frederick FitzRoy | 2,054 | 32.3 | New |
| Majority | Majority | Majority | 38 | 0.6 | N/A |
| Turnout | Turnout | Turnout | 4,203 (est) | 79.4 (est) | N/A |
| Registered electors | Registered electors | Registered electors | 5,293 | | |
| | Conservative hold | Conservative hold | Swing | N/A | |
| | Conservative hold | Conservative hold | Swing | N/A | |