Originally constructed during the Victorian era, St. Martin’s Battery was extensively rebuilt and updated during the Second World War. At the rear of the gun positions, the Victorian brickwork is still clearly visible, along with the contemporary expense magazines. Directly behind the battery is the deep shelter. This was constructed originally as the main magazine to supply the battery guns but was extensively lengthened during the war to become a deep shelter. The deep shelter is now in poor condition, with many parts having suffered from smoke damage and collapse.