Why Britain and Japan need different frigate hulls

Why did Britain choose the large Type 26 while Japan chose the smaller Mogami class if their naval requirements are similar?

Their desired capabilities overlap, but Britain plans for distant South Atlantic, Arctic, and Pacific operations, while Japan operates mainly nearer its Pacific home waters.

Mogami is compared with Type 31 in size while retaining a high level of technical capability. Britain's larger Type 26 is intended for distant operations in the Pacific, Arctic, and South Atlantic, with the South Atlantic especially affecting hull size. Japan is expected to operate more often within its own Pacific region. Similar combat requirements therefore need not produce identical hulls and machinery. Ships associated with the Horizon programme illustrate a proposed alternative: common sensors, missiles, and combat systems with hull and engine arrangements suited to national requirements. Rough seas and ice impose different demands from sustained operations in warmer waters.