Tewin is a village in Hertfordshire, England.
It is situated within the AL6 postcode district, which is within the Welwyn post town.
AL6 is the only postcode district within the Welwyn post town.
The Welwyn post town is within the St Albans postcode area.
Administrative Ward: Hertford Rural South
Administrative District: East Hertfordshire
Administrative County: Hertfordshire
Country: England
UK Parliament: North East Hertfordshire
NHS Local Health Authority: East of England
NHS Region: North, Midlands and the East