Hatfield is a town and civil parish in Hertfordshire, England, in the borough of Welwyn Hatfield. It had a population of 29,616 in 2001, increasing to 39,201 at the 2011 Census. The settlement is of Saxon origin. Hatfield House, the home of the Marquess of Salisbury, is the nucleus of the old town. From the 1930s when de Havilland opened a factory until the 1990s when British Aerospace closed, Hatfield was associated with aircraft design and manufacture, which employed more people than any other industry. 

Hatfield was one of the post-war New Towns built around London and has much modernist architecture from the period. The University of Hertfordshire is based there. Hatfield is north of London and is connected to the capital via the A1(M) and direct trains to London King's Cross, Finsbury Park and Moorgate. As a result, the town has seen a recent increase in commuters who work in London moving to the area. 

In the Saxon period Hatfield was known as Hetfelle, but by the year 970, when King Edgar gave to the monastery of Ely, it had become known as Haethfeld. Hatfield is mentioned in the Domesday Book as the property of the Abbey of Ely, and unusually, the original census data which compilers of Domesday used still survives, giving us slightly more information than in the final Domesday record. No other records remain until 1226, when Henry III granted the Bishops of Ely rights to an annual four-day fair and a weekly market. The town was then called Bishop's Hatfield.
are more people moving to London for work
 work in London moving to the area.