The Bedfordshire Historic Environment Record [HER] contains information on the county's historic buildings and landscapes and summaries of each entry can now be found online as part of the Heritage Gateway website. The earliest evidence for humans in Greenfield is from the Mesolithic Era. A microlith, or minute stone tool was found during field walking [HER 3657] as was a stone tool used for scraping [HER 3870].

The Neolithic Era followed the Mesolithic and evidence from Greenfield comprises a flint scraper [HER 2764]. Another scraper has also been found in the village [HER 3643] this may be Neolithic or it may date to the succeeding Bronze Age. Flint tools continued to be used in the Bronze Age and even into the Iron Age. This is because they were easy to make and durable. Moreover, flint is common is south Bedfordshire and so the raw materials were easily to hand.

Fragments of five Roman vessels, including a stamped Samian cup, were found during excavations for a pipeline in 1965 [HER 112]. The exact location of the discovery is not known, but to the north of Greenfield the pipeline ran through an area of known Roman occupation to the east of Ruxox Farm in Flitwick, where small pieces of mosaic had been found a few years earlier. It is likely that the pottery came from this area. Samian ware was high status pottery. A scatter of Roman tile of the 3rd and 4th centuries AD was found west of Hermitage Farm during field walking [HER 3642].

The Viatores are a group dedicated to finding former Roman roads in the modern landscape. A road from Luton to Marston Moretaine was suggested as a Roman route in 1964 [HER 5020] but there is no definite evidence to support the theory.