• the town of Hitchin and the surrounding villages (Pirton, Holwell, Ickleford, Offley, Lilley, Hexton, St Paul’s Walden, King’s Walden, St Ippolyts, Breachwood Green, Preston, Little & Great Wymondley, Langley, Kimpton and Whitwell), which were transferred from the old constituency of North Hertfordshire. Graveley Ward was added in 2010
  • the town of Harpenden and the villages of Redbourn and Sandridge which were transferred from the St Albans constituency.
  • the village of Wheathampstead which transferred from the Welwyn and Hatfield constituency. Hitchin is an important old market town whereas Harpenden has only expanded from a small village over the last century.