Portkil Battery, 4.7-inch QF battery

Portkil Battery is a pair of coast defence batteries built between 1900 and 1904, located at the southern end of the Rosneath peninsula. They were part of the coastal defences for the River Clyde during the First World War.

The 6-inch battery, which is the western example, includes two gun emplacements, an underground magazine, and the remains of a gun officer's position. To the east is the 4.7-inch Quick Firing battery, which also features two gun emplacements and an underground magazine. The gun emplacements are constructed from reinforced concrete and include locker recesses, shell hoists, and semi-circular aprons to the south. Stairs provide access between the emplacements and lead to a sunken rectangular lightwell courtyard, which is flanked by magazines, shell, and cartridge stores. The interiors of the magazines and stores were not accessible during the visit in 2018.

There are additional later structures, such as sheds and mobile homes, located on and adjacent to the batteries, which were added after the battery closed in 1928. According to Section 1 (4A) of the Planning (Listed Buildings and Conservation Areas) (Scotland) Act 1997, these later sheds and mobile homes are excluded from the listing.