The civil parish includes the villages of Broom and Stanford and the hamlet of Ireland Its eastern fields are on the plain of the River Ivel; its west is hilly.

The principal residence, Southill Park, was one of at least four manors, and was for three generations the home of the local branch of the landed Byng family, the Viscounts Torrington, Navy admirals, by whom it was sold at the end of the 18th century to industrialist Samuel Whitbread.

[2] Central Bedfordshire Council has locally classified the landscape as Lower Ivel Clay Valley (type 4B) where large, open arable fields predominate and the Mid Greensand Ridge (6B) which in addition to arable fields has significant areas of woodland, acid grassland and parkland.

[6] The village centre, Southill Park and west of the parish have low fertility, freely draining, slightly acid loamy soils.

Land to the east of Stanford Road and to the north of the village has highly fertile, freely draining, slightly acid but base-rich soil with a loamy texture.

[10] The Book shows sixteen freemen formerly owned its most valuable entry upon conquest, replaced by two Frenchmen at the time of its compilation in 1086.

Southill landowners in 1086 included gentry Hugh of Beauchamp, Countess Judith (Judith of Lens) who founded nearby Elstow Abbey in 1078, Walter of Flanders, Richard Poynant, William of Cairon and Alric (Wintermilk) who was a Saxon landowner — his very small £0.2-rated estate was substituted by one of equal worth, though valued at more in the interim and having 40% more ploughlands.

Earlier seized were two holdings of Leofwin the noble of Caddington taken on conquest and which holder the Book adds held under King Edward's overlordship.

A sepulchral vault to the Byng family built in rendered brickwork has a round-headed doorway facing their former park to the east.

The fifteenth century west tower has three stages with opposing square and clasping lightly buttressing walls topped by pale-brick-built battlements of differing heights.

"[12]The equivalent in 1914 reads: parish and village with railway station (1½ miles north-west, Midland Railway), east Bedfordshire; parish[...5,734 acres (23.20 km2)], population: 989, [population of] ecclesiastical district: 954; village 3 miles south-west of Biggleswade; Post Office; Telegraph Office at station.

In vicinity is Southill Park, seat".An event was held in the village in March 2007 and an eponymous real ale was brewed by B&T Brewery in Shefford to commemorate the 250th anniversary of the execution of Admiral Byng.

Post Office archives record the issue to Southill on 6 August 1850 of a type of postmark known as an undated circle.