Southill is a village in Dorset, England.
It is situated within the SG18 postcode district, which is within the Biggleswade post town.
SG18 is the only postcode district within the Biggleswade post town.
The Biggleswade post town is within the Stevenage postcode area.
Administrative Ward: Northill
Administrative District: Central Bedfordshire
Country: England
UK Parliament: Mid Bedfordshire
NHS Local Health Authority: East of England
NHS Region: North, Midlands and the East