In 1929, a recently elected Liberal, Sir William Jowitt decided to join the Labour Party and called for a by-election (which implies a single vacancy) to support this change of party, which he won, to take up for two years the position of Attorney General of England and Wales as part of the Government.

[4] 1918–1950: County borough of Preston and urban district of Fulwood:[5] 1983–1997: The Borough of Preston wards of Ashton, Avenham, Brookfield, Central, Deepdale, Fishwick, Ingol, Larches, Moorbrook, Park, Ribbleton, St John's, St Matthew's, and Tulketh.

The boundaries of the re-established constituency corresponded to those of former County Borough, with Fulwood being included in the new seat of Ribble Valley.

1997–2010: The Borough of Preston wards of Ashton, Avenham, Brookfield, Central, Deepdale, Fishwick, Larches, Moor Park, Ribbleton, Riversway, St Matthew's, and Tulketh, and the Borough of South Ribble wards of Bamber Bridge Central, Bamber Bridge South, and Walton-le-Dale.

[6] 2018–2024: In full: Ashton, Brookfield, City Centre, Deepdale, Fishwick and Frenchwood, Plungington, Ribbleton, St Matthews.

Representatives have sat in Parliament for Preston for nearly 800 years, the first recorded names being Willielmus fil' Pauli and Adam Russel.

With the suburban, middle class former Fulwood Urban District area within Ribble Valley (and from 2010 Wyre and Preston North), the southern portion has awarded MPs with much healthier and secure majorities.

Less than a year later, the 2001 general election returned Mark Hendrick with a much healthier 12,200 majority, up against South Ribble councillor Graham O'Hare for the Conservatives and the then local Liberal Democrat leader Bill Chadwick.

In real terms, all three main parties lost support from 1997 - Labour down by over 8,000 votes, Conservatives reduced by over 2,200 and Lib Dems 2,300 lower.

Whilst Mark Hendrick secured less than 50% of the votes cast in 2010, the first time this has occurred at a Preston election since 1983, subsequent results had much stronger Labour majorities.