[n 2] The constituency was created under the Redistribution of Seats Act 1885 that year, which lasted until it was reformed as Gainsborough and Horncastle on a boundary change for the 1983 election.

[3] This relatively vast rural seat north of Lincoln is named after the small market town at its western boundary.

Regeneration projects are attempting to reduce pockets of severe deprivation in the constituency, but most of the area is affluent, albeit remote from many major cities; the closest conurbation is the city of Lincoln to the immediate south.

Scunthorpe and Grimsby are both close enough to the northern edge of the constituency to be significant to residents.

The political parties had been making preparations for an election to take place from 1939 and by the end of this year, the following candidates had been selected; For 1983 – 1992, see Gainsborough and Horncastle (UK Parliament constituency)