Gun stocks did not solve the 15-inch turret bottleneck

Why were 15-inch guns a construction problem when Britain still had many barrels?

The barrel pool survived, but complete turret production had shut down; Britain could maintain guns more easily than manufacture new mountings.

Interwar Britain retained many 15-inch guns and could reline barrels or sustain low-rate barrel production. It did not, however, keep a live production line for complete new 15-inch turrets because no ships then required them. That distinction explains why readily available guns could not simply be fitted to a new class on demand. Vanguard's use of existing mountings reflects the turret-production constraint rather than a shortage of loose barrels alone.