Portkil Battery, 6-inch battery

The buildings are two coast defence batteries, built between 1900 and 1904. Located on the southern end of the Rosneath peninsula, it formed part of the coastal defences of the River Clyde during the First World War.

The 6-inch battery is the western example, comprising two gun emplacements, an underground magazine and the remains of a gun officer's position. The 4.7-inch Quick Firing (QF) battery is to the east, and comprises two gun emplacements and an underground magazine. The gun emplacements are built of reinforced concrete, with locker recesses and shell hoists, and semi-circular aprons to the south. Access stairs between the emplacements lead to a sunken rectangular lightwell courtyard flanked with magazines, shell and cartridge stores. The interiors of the magazines and stores were not seen during the visit (2018).

There are later structures in the form of sheds and mobile homes that are placed on and adjacent to the batteries. These have been added since the battery closed in 1928. In accordance with Section 1 (4A) of the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997 the following are excluded from the listing: all later sheds and mobile homes, on or directly adjacent to the batteries.