Coflein has this down as decidedly Iron Age, but as a defended enclosure rather than anything cursus-y. It was excavated in the early 80s, confiming its prehistoric date (although Coflein doesn’t detail any finds).
A sub-rectangular enclosure, c.75m by 75m, biscected by a N-S hedgeline, best preserved to the W. Defined by up to five lines of scarps or banks, with a hollow-way leading to the SW facing entrance.
Excavation, 1980-2, on the half of the enclosure demonstrated a complex sequence of occupation from the 3rd C. BC to the m.4th C. AD.
coflein.gov.uk/en/site/306992/details/COLLFRYN%2C+ENCLOSURE/
