Excavations of the 'Mithraeum' were initiated in an attempt to find positive evidence of its use. Trenches were inserted fairly randomly but an attempt was made to further define the surrounding wall which had been identified as a possible portico by earlier investigations (see ECC793 and ECC795). A deep shaft was sunk against the outside wall of the main building. The shaft was cut through clay and the depth was so great that the base of the wall could not be reached. A second shaft was sunk in the NE corner of the building where a robber trench was discovered running northwards before turning west. Further investigations showed this to be from a previously unrecognised room and also confirmed the course of the outer walls.<1>