Originally most of Gibraltar's guns were on the coast but Major General Sir John Jones realised that setting them higher up the Rock gave them more range and made them more difficult to hit.

There was a growing realisation that the thickness of the armour carried by battleships at the end of the nineteenth century meant that they were almost impossible to penetrate with even the largest gun.

These batteries would have been unusual with the guns and crews hidden from view because they were so far below the surface that only specially placed observers could see the horizon.

[3] These high angle guns were the antithesis of the famous gun carriage created by George Koehler which were designed to fire at a depressed angle down the side of the rock of Gibraltar and made a major contribution to the Great Siege of Gibraltar.

The parabolic shapes directed the smallest of noises to a microphone which would give an early warning.