[1] In early October 1840, Major-General John Thomas Jones arrived to inspect the defences of Gibraltar.

[2] Jones advised on improvements for Parson's Lodge Battery, which caused eight guns to be installed in 1842.

[1] At the height of its military importance, the battery had three 10-inch (250 mm) rifled muzzle-loading guns that guarded the approaches to Rosia Bay, which is the only natural harbour on The Rock.

[1] The shields later used bolts that were also protected against abnormal loads as they included wooden bushes and had corners filed away to prevent them being snapped when resisting an enemy's shell.

[5] The tunnel was one of two originally created to take large quantities of quarried stone from Camp Bay to the harbour's South Mole when it was constructed in the 1880s.

[8] From about 1725 to 1840 (when a larger battery was built to the left) a smooth bore gun was positioned here to cover Camp Bay.

This contained two MMGs and two SMLE apertures in the cliff face overlooking possible enemy landing areas in Camp and Little Bays.

This large limestone construction replaced its predecessors (see relic to the right) about 1842 in accordance with recommendations of Major-General John Thomas Jones, and was surmounted, at the time, by eight guns.

These included "spark free" copper fittings, rope shoes and the obvious measure of lighting magazines through plate glass fronted passages or niches.

Made in Woolwich, they fired a 400 lb (180 kg) projectiles to a range of about 4,500 yards (2.6 miles: 4 km).

The gun fired and was protected, from seabourne attack, by a sandwich of armour plate and tyeack, specially invented for use here and known universally as "Gibraltar Shields".