As might be expected in an area close to a major river, in this case the Great Ouse, the local parishes contain a good deal of evidence of settlement before the Norman Conquest. The Bedfordshire Historic Environment Record [HER] details all these sites and find spots and is now on-line as part of the Heritage Gateway site. This article is taken from the various entries in the HER.
The most interesting feature in Chawston is a Bronze Age barrow at Round Hill [HER 1494]. The site consists of a bowl barrow situated in a prominent position on high ground to the north-west of the modern A421. The HER describes it thus: "The barrow mound stands amidst a wide area of cultivated fields and is a conspicuous local landmark. It is circular in plan, measuring approx 21 metres in diameter, and survives to a height of approx 1.7 metres, with steep sloping sides descending from a level area on the summit which measures 10 metres across. The barrow, which is apparently unexcavated, is thought to be an outlying example associated with a pattern of Bronze Age barrows located along the gravel terraces flanking the River Great Ouse. Unlike the "Round Hill", however, most of these are only visible as cropmarks which have been recorded from the air. This distribution, which comprises some 200 monuments in the upper and middle sections of the Great Ouse valley, includes a group of five on the north side of the junction of the Rivers Great Ouse and Ivel (approx 2 kilometres south-east of the Round Hill). These were excavated in the early 1970s, prior to gravel extraction, and found to contain burials dating from c.1800 B. C. A fieldwalking programme undertaken in the late 1970s identified a pattern of broadly contemporary worked flint which concentrated on this barrow group and extended up the side of the river valley to the west of Roxton. The limit of this survey area came within 500 metres of the Round Hill. The site is a Scheduled Ancient Monument (No 27112). It has in the past been thought to be a windmill base or a Roman burial mound".
Another Bronze Age feature is a group of cropmarks north of Chawston Lane [HER 8818]. These include a ring ditch, linear features and possible small rectangular enclosure shown on aerial photographs. Ring ditches are, as the name suggests, roughly circular ditches and may be the remains of barrows or round houses. Another group of Bronze Age cropmarks lies at Spinney Road [HER 1836]. The marks comprise a number of irregular linear features, thought to be prehistoric, and part of another possible ring ditch, recorded from aerial photographs.
More cropmarks lie east of Bridge Farm [HER 1651]. They are irregular and may be part of a sub-rectangular enclosure. They are thought to be prehistoric but no more specific era can be allotted to them without material evidence.
Another set of cropmarks [HER 745] lie north-west of the Black Cat Roundabout where the A421 joins the A1. The HER describes them as: "A linear block of linked sub-rectangular enclosures visible on aerial photographs, one or more containing circular structures possibly of some status. Archaeological investigations just to the south of the cropmarks uncovered peripheral features relating to late Iron Age or Roman occupation. A Romano-British strap end was found north of Chawston Lane [HER 16193] along with later material. A Roman brooch [HER 16038] of a ten petalled design was found within these cropmarks. It was in the form of a flower or star and each petal ends in a small round disc. The plat has a raised central knob inlaid with yellow enamel and surrounded at the base by a ring scored by tiny transverse lines. Alternate petals were red with orange discs.
To the west of Roxton Road a trench was excavated containing three roughly parallel gullies and eleven pits or postholes, four of which may make a rectangular structure [HER 13413]. One of the larger pits may have been the southern end of an early Anglo-Saxon partly sunken dwelling called a grubenhaus. The evidence for this is its large width and shallow depth; it also contained a posthole. Discoveries of grubenhauser are rare, they date from the 5th to the 7th centuries and so are linked with the first waves of Anglo-Saxon migration into England.