The Light Fleets were the first British aircraft carriers where the ship's air group was seen as the 'main armament'; any mounted weapons were to be for close-range anti-aircraft defence.
The Colossus design called for six quadruple barrelled 2 pounder gun mounts, and 16 twin Oerlikon 20 mm cannons.
Two 4-inch (102 mm) guns were originally included, but an increase in the design's flight deck length in March 1942 saw them displaced.
The ships were unarmoured, as increasing the size of the vessels was deemed more important than protection.

Lessons learned during the early part of the Pacific War showed the superiority of the Bofors 40 mm gun to other anti-aircraft weapons.
By the end of the war, all Colossus-class ships had swapped all their other weapons for Bofors in single and twin mountings, and the Majestic design had been modified to carry 30 of the guns: 18 single mountings, and 6 twin mountings.
The number of Bofors carried by the Light Fleets was reduced after the war, with British ships carrying only eight.
The Light Fleets were the first British aircraft carriers where the ship's air group was seen as the 'main armament'; any mounted weapons were to be for close-range anti-aircraft defence. The Colossus design called for six quadruple barrelled 2 pounder gun mounts, and 16 twin Oerlikon 20 mm cannons. Two 4-inch (102 mm) guns were originally included, but an increase in the design's flight deck length in March 1942 saw them displaced. The ships were unarmoured, as increasing the size of the vessels was deemed more important than protection.
Lessons learned during the early part of the Pacific War showed the superiority of the Bofors 40 mm gun to other anti-aircraft weapons. By the end of the war, all Colossus-class ships had swapped all their other weapons for Bofors in single and twin mountings, and the Majestic design had been modified to carry 30 of the guns: 18 single mountings, and 6 twin mountings. The number of Bofors carried by the Light Fleets was reduced after the war, with British ships carrying only eight.
1942 Design Light Fleet Carrier