Until the enclosures and the metalling of roads the ruts and hoof-marks of the Icknield Way were probably spread over a width of from a hundred yards to a mile, according to convenience or necessity; from century to century its course might vary even more. Thus the modern road between Kentford and Newmarket is at several points some distance from the Cambridge and Suffolk boundary, which is supposed to follow the Icknield Way.
A deed already mentioned proves that the road was known in Newmarket itself.
Beyond Newmarket the modern road is marked as the Icknield Way, but is only a parish boundary, or rather close to one, for one mile in the first eight, and is not authenticated by any known documents. Nor is any parallel road in the same direction a boundary line. That it is on an old line of road is certain from the number of tumuli which formerly dotted the surrounding heath. It goes through three dykes, two, eight, and thirteen miles from Newmarket, and it has been conjectured both that the dykes defend the road and that the road was made by an invader to pierce the dykes; one antiquary asserts that the fosse of the Brent Ditch “has evidently been filled up to admit the road.” From a little beyond the eighth milestone and Fleam Dyke the road is a parish boundary, with very short interruptions between the eleventh and twelfth, as far as the fourteenth, where it becomes the Cambridge and Essex boundary. Turning west beyond the fifteenth, it is followed for some distance by the county boundary, and is thrice rejoined by it, the third time for two miles before entering Royston. By this sharp turning to the west it avoids a Roman camp at Great Chesterford, and passes what Camden called the “ancient little city” of Ickleton, where in his time traces of the “Burrough banks” could plainly be seen. Near Abbey Farm at Ickleton are the remains of a priory. Where it is again a county boundary beyond Ickleton, near “a tumulus opened by the late Lord Braybrooke,” it is a farm road, and continues as such in a clear line through arable land and alongside hedges, until it joins the main road into Royston. Here it goes over Burloes Hill, where many indications of ancient burials have been found.