Great Barford has a wealth of Stone and Bronze Age sites, discovered from aerial photographs of cropmarks and isolated finds. Perhaps this should come as no surprise given the parish's location next to a major river (the Great Ouse). The Bedfordshire Historic Environment Record [HER], now on-line as part of the Heritage Gateway site, details the following sites and finds.

A Palaeolithic handaxe of white flint was found in river gravels at Great Barford [HER 9928]. The Historic Environment Record notes: "the white flint is unusual for the Ouse where it is more usual to find brown flint hand axes". This is the earliest evidence for human activity in the parish.

A number of sites can only be described in general as prehistoric due to lack of firm dating evidence. They include:

• A dispersed spread of linear & enclosure cropmarks identified from aerial photographs north of Creakers [HER 1632]. Some are shown as close boundaries on a pre-enclosure map. Some sub-rectangular enclosures may be prehistoric.
• More cropmarks, south-west of Brewer's Hall Farm, show a complex grouping of irregular enclosures on an eastern slope of a small stream valley [HER 1800]. The features have not been traced on the ground, and no dating evidence has been retrieved, but they are thought to be prehistoric.
• More cropmarks to the north of the village seem to show a group of small, mainly sub-rectangular enclosures located on a slight ridge [HER 16750].

A number of ring ditches have been identified from aerial photographs. As the name suggests these are roughly circular ditches which represent the remains of round barrows. They are usually ascribed to the Bronze Age. The following have been identified in Great Barford:

• Cropmarks south-west of Bridge Farm show an area of cropmarks, comprising ditches and rectangular enclosures likely to be Roman, with two Bronze Age ring ditches to the north of the enclosures [HER 596].
• Cropmarks south-west of the village include a ring ditch [HER 600].
• Cropmarks east of College Farm show a scatter of ring ditches and a group of rectilinear enclosures [HER 604]. Bronze Age occupation evidence was located during a field evaluation in 1998 at the south end of the area, east of College Farm. Iron Age occupation was also discovered.
• An isolated ring ditch, has been recorded as a cropmark east of Roxton Hill House [HER 3573].
• Another ring ditch has been identified north-east of Ousebank Farm with an associated  small, sub-divided oval enclosure which may date to the late Neolithic [HER 9937].
• A ring ditch has been identified as a cropmark east of Ousebank Farm [HER 15259].
• A possible cropmark north of Barford House [HER 16769] appears to be an isolated ring ditch with an external diameter of about 16 metres with a metre wide ditch. Field walking produced very little flint or other finds.

When the Anglian Water Authority was doing work at Barford Lock in 1975 a Bronze Age spearhead was picked up from the river bank where they were working [HER 9816]. The find was recorded by Luton Museum and retained by finder. The finder also reported five or six Neolithic stone axe heads, which he put in a heap, but children threw into the river!