Members of Humber Field Archaeology are completing a three-month dig on the site of the former Bonus Electrical building near Humber Street, once a densely populated area of the Old Town.

But although they are delighted by the finds – including the possible location of the Humber Gate, a medieval entrance to the town – they have so far failed to discover Hull's first Carmelite friary, as hoped.

Among the booty which has lain hidden for centuries, however, is a 14th or 15th century Humberware drinking jug made in the area of West Cowick near Goole, a cess pit, pottery, an 18th century cannon ball which may be linked to the Siege of Hull and the English Civil War, and a fragment of brass chainmail armour.

Tests will now be carried out and discussions held with Hull Council and developers to see what can be preserved before the site becomes part of the redeveloped Fruit Market.

Project manager Trevor Brigham said the team was excited about the possible discovery of the gate and evidence of housing and warehousing.

He said: "It's very significant because it shows the density of occupation in the area. From a planning point of view it's interesting because it shows how Hull was regenerating itself every generation. The gate was situated behind the (town) wall and spanned the street, which is pretty unusual. It seems to have been rebuilt in a brick similar to a 17th century artillery fort on the other side of the road, which was found in 2006."

Mr Brigham said further efforts may be made to find the elusive friary. The Carmelites were given land in the area in the 1290s, while the Augustinians later developed a friary on the site of what is now a magistrates' court.