Programme of investigation comprising evaluation, excavation and a watching brief by D Saxby of MOLA. Evaluation revealed evidence of Iron Age and Saxon activity in three areas of the site, with the subsequent excavation targeting these areas. Within the middle of the site a 0.4m-thick layer of sand was revealed that produced 1544 Early Mesolithic flints including microlithic flint points, microburins and at least four core adze fragments and a scraper (c 9600–7600 cal BC).

Oxford Archaeology South (OAS) was commissioned by Andrew Josephs Ltd, on behalf of J and J Franks Ltd, to undertake an archaeological evaluation of land at Mercers Farm, near Nutfield, Surrey (centred on TQ 3050 5200) ahead of proposed mineral extraction. The work was undertaken between 3rd - 27th January 2012. A total of 94 trenches were excavated across the site. Evidence was found for activity from three main periods: the earliest spanning the late Bronze Age to early Iron Age; medieval agricultural use; and post-medieval activity.

The excavation by Greg Priestley-Bell, revealed a large number of archaeological features which ranged in date from the Late Bronze Age/Early Iron Age to postmedieval/modern periods. The majority, however, were dateable to the Iron Age and are described below. Details of the post-medieval and modern features are housed with the archive.

Test pitting by C Hayward of SyAS, produced a small quantity of pottery of Late Bronze Age, Middle Iron Age and late Roman date. (458)

Geophysical survey in 2014 by A Sassin and D and A Graham of SyAS on a site first noted by J Hampton on an aerial photograph. The survey confirmed the presence of a probable Late Iron Age/early Romano-British farmstead enclosure. Roman roof tile and pottery was noted during the survey and coins and other objects of Roman date from the same area have been recorded by the Portable Antiquities Scheme.

A third phase of excavation by K Welsh of OA in advance of continued mineral extraction, revealed a considerable degree of truncation, previously noted across the site (SyAC 99, 232) that became increasingly marked towards the west. As a result, few archaeological features survived in the Phase 3 area other than a sparse scatter of more deeply cut pits, one of which, probably a waterhole, produced a socketed copper-alloy axe of the Sompting type, variant Cardiff II. The type dates from between c 800 and 600 BC and is found throughout much of southern England, the Midlands and South Wales.

Evaluation by T Collie of SCAU on the site of the new Spelthorne fire station revealed shallow linear ditches and a pit, all of probable Iron Age date.

Excavation by T Munnery of ASE of two of seven identified areas (SMS1 and WB6) highlighted as being of archaeological significance following evaluation (SyAC 94, 364).

Further excavation by the Roman Studies Group of SyAS led by D Bird in the field to the north-east of the Scheduled villa area revealed evidence for probably two consecutive later Iron Age enclosures on the hilltop together with eleven flat-bottomed pits to add to the three found in 2014. Quernstones and other finds confirmed the idea that these were probably for grain storage. Burnt clay, probably from wattle-and-daub oven domes and large quantities of burnt carrstone in pit fills, suggested Late Iron Age activity.

Excavation by A Haslam of PCA targeted three areas of the site, identified following earlier evaluation (SyAC 99, 218). Area 1 was situated in the south-western corner of the site. It revealed two parallel, north-west/south-east orientated ditches, interpreted as a droveway, and a series of small pits and postholes that formed a sub-rectangular enclosure, possibly an animal pen or paddock, to their east. All were of probable Late Bronze Age or Early Iron Age date. A further sub-pen was identified within the south-eastern corner of the enclosure.