Why the Royal Navy kept developing landing craft between the wars

How did the Royal Navy get away with developing landing craft during the interwar period?

Nothing prohibited it, and Gallipoli gave the navy a compelling operational reason to keep investing in amphibious craft.

The Royal Navy faced no stated prohibition on developing landing craft between the wars. It retained the interest and money to continue the work. Gallipoli provided a concrete operational reason for specialist landing equipment. That experience could answer objections whenever the purpose of continued development was questioned.