Harpenden has been part of several different parliamentary constituencies over time. Apart from two short periods when Liberals were elected the seats containing Harpenden have always returned Conservatives. In the mid-nineteenth century Harpenden was part of St Albans or Mid-Herts Division, but from 1852 to 1885 St Albans was deprived of its MP after a notorious vote-buying scandal. The first elected MP in 1885 was Viscount Grimston (Conservative), the 3rd Earl of Verulam. He was succeeded in 1892 by Vicary Gibbs, who had to resign in 1904 (over a business deal involving the sale of warships to the Chilean navy), and the Liberal John Slack won the ensuing by-election. The Conservatives won the seat back in 1906 and Sir Hildred Carlile served as MP until 1918, when Harpenden was incorporated into the new Hemel Hempstead Division. In 1918 women (over 30) had the vote for the first time, and all men over 21 regardless of income.
The 1918 election was won by the Coalition Conservative, Gustavus Arthur Talbot, and on his death in 1920 by John Davidson (elected unopposed). In the 1923 election the seat was narrowly won by a Liberal, John Freeman Dunn, but Davidson regained the seat in 1924 and served as MP until his elevation to the peerage in 1937. As Private Secretary to Andrew Bonar Law he was involved with decision to appoint Stanley Baldwin rather than Lord Curzon as PM in May 1923. He held several ministerial posts and served as Chairman of the Conservative Party from 1926-30.
His wife, Lady Frances Davidson, won the resultant by-election and served as MP until 1959, and later entered the House of Lords as Baroness Northchurch. In 1945 she was the only woman Conservative MP. On her retirement the seat was held by James Allason until boundary revisions in 1974 when Harpenden became part of St Albans Division. Allason narrowly won the February 1974 election but in the subsequent October election of that year the new Hemel Hempstead seat was won by Labour’s Robin Corbett.
The St Albans seat had been held from 1970 by Victor Goodhew, who continued to hold the seat after the boundary changes until he retired in 1983. The seat was won by Peter Lilley in 1983 until the next round of boundary changes in 1997, when the new constituency of Hitchin and Harpenden was formed. Peter Lilley chose to move from St Albans to Hitchin and Harpenden, for which he was still the MP after the 2015 election, while his former seat of St Albans was won by Labour’s Kerry Pollard in 1997. Peter Lilley served in several ministerial posts and was deputy Leader of the Conservative Party from 1998-99.
Harpenden residents who became MPs elsewhere include Leslie Burgin (Nat. Liberal, Luton, 1929-45), Charles Hill (Con, Luton, 1950-63), Robin Corbett (Lab, Hemel Hempstead, 1974-79, Birmingham Erdington, 1983-2001) and Kelvin Hopkins (Lab, Luton North, 1997-).
The election results from 1885 onwards were as follows:
St Albans (Mid-Herts) Division
- 1885 Viscount Grimston (Con) 4108 J. Coles (Lib) 3037
- 1892 Vicary Gibbs (Con) 3417 T.M. Harvey (Lib) 2573 W.H. Brigham Cox (Ind C) 1580
- 1895 Vicary Gibbs unopposed
- 1900 Vicary Gibbs unopposed
- 1904 (By-) John Bamford Slack (Lib) 4757 V. Gibbs (Con) 4635
- 1906 Hildred Carlile (Con) 5856 Slack (Lib) 5304
- 1910 (Jan) Carlile 7323 H.R. Beddoes (Lib) 5271
- 1910 (Dec) Carlile 6809 R.C. Phillimore (Lib) 4777
Hemel Hempstead Division
- 1918 Gustavus Arthur Chetwynd Talbot (Con) 10070 Jesse Hawkes (Lab) 2913
- 1920 (By-) John Colin Campbell Davidson (Con) unopposed
- 1922 Davidson (Con) 11847 John H Clynes (Lab) 5726
- 1923 John Freeman Dunn (Lib) 8892 Davidson (Con) 8875
- 1924 Davidson (Con) 12985 Dunn (Lib) 7994 Amy Sayle (Lab) 1553
- 1929 Davidson (Con) 15145 Charles T. Le Quesne (Lib) 11631 A.E.R. Millar (Lab) 3624
- 1931 Davidson (Con) 21946 Le Quesne (Lib) 8021 Millar (Lab) 2677
- 1935 Davidson (Con) 20074 Margery Corbett Ashby (Lib) 7078 C.W. James (Lab) 4951
- 1937 (By-) Lady Frances Davidson (Con) 14992 Ashby (Lib) 7347 James (Lab) 3651
- 1945 Lady Davidson (Con) 19536 Miss D W Mobbs (Lab) 14426 Wing Com. Trotter (Lib) 10219
- 1950 Lady Davidson (Con) 22022 R. Moss (Lab) 15165 P.A. Stevens (Lib) 6696
- 1951 Lady Davidson (Con) 25620 Norman MacKenzie (Lab) 18220
- 1955 Lady Davidson (Con) 25648 MacKenzie (Lab) 19512 E. Saich (Lib) 5111
- 1959 James Allason (Con) 30189 B.F.C. Floud (Lab) 21954 M. Neilson (Lib) 8358
- 1964 Allason (Con) 31119 G.D. Hitchcock (Lab) 26273 A.J. Whiteside (Lib) 11986
- 1966 Allason (Con) 31742 Robin Corbett (Lab) 29704 Whiteside (Lib) 9970
- 1970 Allason (Con) 40417 P.A. Fletcher (Lab) 28067 A.J. Wilson (Lib) 9274
St Albans Division
- 1974 (Feb) Victor Goodhew (Con) 26345 Anthony.C. Shaw (Lib) 17924 Danny Bernstein (Lab) 14077
- 1974 (Oct) Goodhew (Con) 24436 Edwin Hudson (Lab) 15301 Shaw (Lib) 14614
- 1979 Goodhew (Con) 31301 David Picton (Lib) 14057 John Greaves (Lab and Co-op) 13638
- 1983 Peter Lilley (Con) 29676 Sandy Walkington (Lib) 21115 Rita Austin (Lab) 6213
- 1987 Lilley (Con) 31726 Walkington (Lib) 20845 Tony McWalter (Lab) 6922 E.V. Field (Green) 788 W.H.Pass 110
- 1992 Lilley (Con) 32709 Monica Howes (Lib Dem) 16305 Kerry Pollard (Lab) 12016 Craig Simmonds (Green) 734 David Lucas (Natural Law) 161
Hitchin and Harpenden Division
- 1997 Peter Lilley (Con) 24038 Rosemary Sanderson (Lab) 17367 Chris White (Lib Dem) 10515 D. Cooke (Natural Law) 290 Jim Horton (Soc Alternative) 217
- 2001 Lilley (Con) 21271 Alan Amos (Lab) 14608 John Murphy (Lib Dem) 8076 John Saunders (UKIP) 606 Peter Rigby (Ind) 363
- 2005 Lilley (Con) 23627 Hannah Hedges (Lib Dem) 12234 Paul Orrett (Lab) 10499 Saunders (UKIP) 828 Rigby (Ind) 199
- 2010 Lilley (Con) 29869 Nigel Quinton (Lib Dem) 14598 Oliver de Botton (Lab) 7413 Graham Wilkinson (UKIP) 1633 Richard Wise (Green) 807 Others 109, 108, 90, 50
- 2015 Lilley (Con) 31488 Rachel Burgin (Lab) 11433 John Stocker (UKIP) 4917 Pauline Pearce (Lib Dem) 4484 Richard Wise (Green) 3053.
- 2017 Bim Afolami (Con) 31189 John Hayes (Lab) 19158 Hugh Annand (Lib Dem) 6236 Richard Cano (Green) 1329 Ray Blake (Ind) 629 Sid Cordle (Christian Peoples) 242
- 2019 Bim Afolami (Con) 27719 Sam Collins (Lib Dem) 20824 Kay Tart (Lab) 9959 Sid Cordle (Ind) 268 Peter Marshall (Ind) 101