Why Royal Navy carrier nuclear options stayed limited

Why were Red Beard and WE.177A the principal nuclear weapons available to Royal Navy carrier jets?

Those were the weapons assigned, and cost plus the end of the large-carrier program made further naval variants unattractive.

The limited selection of Red Beard and WE.177A is explained chiefly through weapon allocation and cost. The Buccaneer could carry the WE.177 A, B and C variants, while Royal Navy aircraft primarily received A. The B and C versions are described as thermonuclear alternatives. The A variant entered service in 1966, shortly before the retreat from large carriers reduced the future of this naval role. On that explanation, the shrinking carrier programme weakened the case for assigning further variants or expanding the specialized naval nuclear inventory.