Why a trade-protection carrier needed 16,000 tons

Would Britain use a 13,000-ton Colossus-style carrier for peacetime trade protection?

Probably not; a roughly 16,000-ton design better supplied the endurance, self-defense, and operational independence required far from bases.

A trade-protection carrier operating in the South Atlantic needed endurance, workshops, defensive weapons, and independence from distant bases. A 12,000- or 13,000-ton Colossus-type ship was a 1942 war-emergency derivative of Unicorn, stripped of support features to simplify construction. That austerity made sense during war but not for a peacetime cruiser-carrier expected to work far from the Falklands, Cape Town, or Caribbean bases. The roughly 16,000-ton concept offered about 36 aircraft and stronger self-defense. Its extra displacement bought operational independence rather than merely a larger air group.