Spigot mortar emplacement of the Second World War Coastal Crust, within the compound of the Cross Keys Swing Bridge. The mortar was used in a prepared position consisting of a concrete cylinder, set within a pit measuring about 7ft across. Incorporated in the cylinder was a steel pintle, upon which the mortar sat and could be rotated. The mortar was designed to fire a 14lb bomb in both flat and arcing trajectories. This particular emplacement was likely sited here to cover the Cross Keys Bridge and its approaches, and to target craft coming up the adjacent River Nene. {1}{2}