An aerial photo of the site- an Iron Age enclosure and two Bronze Age barrows can be seen cutting into the bright chalk.
Another page shows some Iron Age coins found at the site. They’re from the first half of the first century BC:
canterburytrust.co.uk/schools/gallery/gall05a.htm
More details in this document:
canterburytrust.co.uk/annreps/pdfs/2001/003.pdf