Why Type 26 moves to a five-inch gun

Why is Type 26 adopting the US five-inch gun instead of the Royal Navy's 4.5-inch weapon?

The larger user base makes future development and support easier to share internationally.

The 4.5-inch weapon remained capable, but its shrinking user base left Britain carrying most of the cost of future development. Moving to the widely used five-inch family lets the Royal Navy share technical and ammunition investment with the United States and other operators. Commonality also gives the Type 26 access to a broader support and improvement ecosystem over the gun's service life. The choice is therefore explained through long-term procurement and development economics rather than a claim that the older calibre had suddenly become ineffective.