When the great west doors of York Minster swing open on Thursday and the Queen makes her way along the nave of the packed church for the ancient service of distributing Maundy Money, she will also be walking towards a small pit from which human bones have been pouring by the barrow load, the remains of some of the earliest Christians to worship on the site.

Tantalising finds include 30 skulls and a jumble of bones used to backfill a trench by the medieval builders of the present cathedral, and a man whose stone-lined and lidded grave was chopped off by Walter de Gray's 13th-century walls, leaving only his shins and feet in place.

Potentially the most significant finds are two nondescript round holes, with groundwater bubbling up through the mud. They are post holes that could date from the time of the earliest Christian church on the site, after the Roman empire disintegrated in the 5th century and before raiding Vikings arrived in the 8th century and the Normans in the 11th century.

Remains of Eboracum, the Roman fortress and town, jut through the fabric of today's city, and the Viking remains of Jorvik including foundations of timber houses, wharves and shops, found in the 1970s during construction of a shopping centre, have become a visitor attraction. But little is known of the period in between....