Ministry of Defence Building L145 (Group F Incorporating Mills)

The Ministry of Defence Building L145, also known as the Gunpowder Incorporating Mills, was built in 1878 and later converted for cordite incorporation around 1898-1899. It features English bond yellow brick construction with hipped slate roofs on both the Engine House and Boiler House. The cross wings have brick walls that separate the bays and extend into coped gables that break 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 eastern end, flanked by three-bay cross wings on the north and south sides for gunpowder incorporating operations. It is a single storey, with the Engine House being taller than the rest. The Engine House features a chamfered brick plinth and a brick dentil cornice, with paired segmental-arched windows set in recessed panels on the upper parts of the east and west elevations. The Boiler House, consisting of four bays by one, has mid-20th century windows inserted into each bay and a gauged red brick semi-circular arch above the east door.

The interior resembles other incorporating mills but has undergone significant alterations and lacks the original gearing machinery that was once beneath the cross wing floors. This building is noted as the most altered of an important group of incorporating mills, with its plan closely modeled on the earlier Group C Incorporating Mills, Building L157, constructed in 1861.