In 1922, Dr Hargreaves of Castle Garth House excavated within a bend of the River Wharfe near the centre of Wetherby. Rectangular walls were revealed and interpreted as belonging to a ‘donjon’ (castle keep) of the late 12th  or early 13th century, and these were incorporated as a garden feature. Hargreaves built a house in the centre of the site and further houses were later added to either side.

In 2003, proposals for a new residential development led to NAA carrying out an assessment and evaluation. Trial trenching demonstrated the survival of significant archaeology, and plans for the development were modified to retain the castle keep and other remains. Planning permission was granted subject to archaeological conditions, and excavation was carried out in 2004–05 during demolition and construction works.

The excavations revealed long-standing human use of the site represented by Mesolithic, Neolithic and Early Bronze Age worked flints and Neolithic Peterborough Ware pottery, an Iron Age burial and pottery. Two stone structures and an array of finds dated to the Romano-British period, and pottery and sheep and pig bones, radiocarbon dated to the 7th or 8th century, indicated Early Anglo-Saxon occupation.

It is possible that the castle fortified an Anglo-Saxon manor. Pottery finds suggested persistent occupation of the site from the 10th or early 11th century to the mid- to late 12th century, and deposits beneath the castle defences demonstrated occupation prior to its construction.

The castle keep was rectangular, 20m by 17.5m with walls typically 4.7m thick, which is similar in size to the 12th-century keeps at Newcastle upon Tyne, Richmond and Scarborough. The central part of the site seems to have been an open bailey, with lower areas made-up with soil and a cobbled surface. Medieval horseshoes and horseshoe nails found there suggested it may have been used by mounted troops and retainers.

Upstanding remains of two opposing rampart terminals were identified, with a roadway passing between them. Other medieval features included pits, a roadside ditch and midden deposits. Beyond the rampart, an unrelated NAA project in 2006 identified the castle ditch running below Scott Lane.

The pottery assemblage included Torksey-type wares of 10th- to 11th-century date. Most of the assemblage comprised Gritty Wares of 11th- to early/mid-13th-century date, including a new type, Handmade Yorkshire Gritty Ware. Very little later pottery was recovered, suggesting that occupancy of the castle was a short-lived affair. Metal finds, such as padlock keys, gilt-bronze decorative strips and an elaborate strap-end, indicated high-status occupation. Ironwork was utilitarian, mostly knives and structural fittings. The only overtly military find was an arrowhead. Other finds included a crane-bone flute and a whetstone. Animal bones found included a high proportion of pig remains, haunches of venison and a wide range of other wild animals, birds and fish.

There is no early documentary evidence for the castle at Wetherby, and the circumstances of its construction and demise are uncertain. It can be inferred from what evidence is available that it was built by the de Denby family, probably in the late 11th or early 12th century. This date was supported by the excavations, which further suggested that occupation ended in the later 12th century, with very little activity thereafter.

A suggested scenario for demolition of the castle is Henry II’s purge of ‘adulterine’ castles after 1154 following the Anarchy of Stephen’s reign. Secondary sources state that stone from the castle was used to build Wetherby Bridge in the 1230s, and no mention is made of a castle in the grant of Wetherby to the Knights Templar in 1238, complementing the archaeological evidence that the castle no longer stood by that date.

The work at Wetherby Castle was a complicated investigation, with each stage informed by a separate project design. Weekly site meetings between the four stakeholders in the project—Country and Metropolitan Homes Northern, West Yorkshire Archaeology Advisory Service, English Heritage and NAA—ensured smooth running of the concurrent demolition, building and archaeological works. A good day-to-day working relationship between the construction manager and NAA’s supervisor meant that all contractors were able to operate safely with one another on an awkward site with restricted access. This project provides an excellent model for similar, future developments.