In the Saxon period Hatfield was known as Hetfelle, but by the year 970, when King Edgar gave 5,000 acres (20 km2) 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.
Hatfield House is the seat of the Cecil family, the Marquesses of Salisbury. Elizabeth Tudor was confined there for three years in what is now known as "The Old Palace" in Hatfield Park. Legend has it that it was here in 1558, while sitting under an oak tree in the Park, that she learned that she had become Queen following the death of her half-sister, Queen Mary I. She held her first Council in the Great Hall (The Old Palace) of Hatfield. In 1851, the route of the Great North Road (now the A1000) was altered to avoid cutting through the grounds of Hatfield House.
Church of St Etheldreda in Old Hatfield.
The town grew up around the gates of Hatfield House. Old Hatfield retains many historic buildings, notably the Old Palace, St Etheldreda's Church and Hatfield House. The Old Palace was built by the Bishop of Ely, Cardinal Morton, in 1497, during the reign of Henry VII, and the only surviving wing is still used today for Elizabethan-style banquets. St Etheldreda's Church was founded by the monks from Ely, and the first wooden church, built in 1285, was probably sited where the existing building stands overlooking the old town.
In 1930 the de Havilland airfield and aircraft factory was opened at Hatfield and by 1949 it had become the largest employer in the town, with almost 4,000 staff. It was taken over by Hawker Siddeley in 1960 and merged into British Aerospace in 1978. In the 1930s it produced a range of small biplanes. During the Second World War it produced the Mosquito fighter bomber and developed the Vampire, the second British production jet aircraft after the Gloster Meteor. After the war, facilities were expanded and it developed the Comet airliner (the world's first production jet liner), the Trident airliner, and an early bizjet, the DH125.
British Aerospace closed the Hatfield site in 1993 having moved the BAe 146 production line to Woodford Aerodrome. The land was used as a film set for Steven Spielberg's movie Saving Private Ryan and most of the BBC/HBO television drama Band of Brothers. It was later developed for housing, higher education, commerce and retail. Part of the former British Aerospace site was intended to be the site of a £500 million new hospital to replace the Queen Elizabeth II Hospital in Welwyn GC and a new campus for Oaklands College, but both projects were cancelled.
Today, Hatfield's aviation history is remembered by the names of certain local streets and pubs (e.g. Comet Way, The Airfield, Dragon Road) as well as The Comet Hotel (now owned by Ramada) built in the 1930s. The Harrier Pub (formerly The Hilltop) is actually named after the Harrier bird, not the aircraft, hence the original pub sign showing the bird. The de Havilland Aircraft Heritage Centre, at Salisbury Hall in nearby London Colney, preserves and displays many historic de Havilland aeroplanes and related archives.
Hatfield New Town centre, looking west along its axis.
The Abercrombie Plan for London in 1944 proposed a New Town in Hatfield. It was designated in the New Towns Act 1946, forming part of the initial Hertfordshire group with nearby Stevenage, Welwyn Garden City and Letchworth. The Government allocated 2,340 acres (9.5 km2) for Hatfield New Town, with a population target of 25,000. (By 2001 the population had reached 27,833.) The Hatfield Development Corporation, tasked with creating the New Town, chose to build a new town centre, rejecting Old Hatfield because it was on the wrong side of the railway, without space for expansion and "with its intimate village character, out of scale with the town it would have to serve." They chose instead St Albans Road on the town's east-west bus route. A road pattern was planned that offered no temptation to through traffic to take short cuts through the town and which enabled local traffic to move rapidly.
Hatfield retains New Town characteristics, including much modernist architecture of the 1950s and the trees and open spaces that were outlined in the original design. As of 2017, a redevelopment of the town centre is planned.