Ministry of Defence Building L148 (Group G Incorporating Mills)

The Ministry of Defence Building L148, part of the Royal Gunpowder Factory, was constructed between 1888 and 1889 and later converted for cordite incorporation around 1898 to 1899. It features English bond yellow brickwork with hipped slate roofs on the Engine House and Boiler House. The cross wings have brick walls that separate the bays and rise as coped gables through the felt and slate roof. Mid-20th century replacement walling has been added to what were originally wood and canvas side walls.

The building has a T-plan layout, with a central Engine House and a Boiler House at the east end, flanked by cross wings for the gunpowder incorporating mills. It is a single storey structure, with the Engine House being taller. The Engine House and Boiler House have a chamfered brick plinth and a brick dentil cornice. The Boiler House consists of four bays, each defined by brick pilasters, originally featuring segmental brick arches over windows with blind rectangular panels below and an east doorway with a keyed semi-circular arch. The Engine House showcases rubbed red brick semi-circular arches over paired windows on the east and west elevations.

The interior is noted to have a roof structure and features similar to those of another building, L157, upon which it was modeled. An open verandah was located along the west front. Additionally, there was a coal yard on the south side of the Boiler House, and the building was served by a tramline to the west. It underwent repairs following an explosion in 1902.