A Batch 3 River could add aviation support and endurance

How might a Batch 3 River-class offshore patrol vessel differ from Batch 2?

It could be longer and add a proper hangar, aviation stores, more endurance, and possibly stronger weapons for the presence role.

A Batch 3 River could be more than a lightly revised Batch 2. A longer hull could support a proper hangar, extra aviation stores, and greater endurance while retaining a similar flight deck. A weapons upgrade would become a design question rather than a certainty. In the wider force structure, Type 31 handles general frigate work while a later River derivative takes on presence missions.