I wondered why Britain was pushing ships to the Pacific (and east of Suez in general) when the small Royal Navy has missions in NATO waters that should more than occupy their assets.
But it seems as if the British are taking on a mission to stabilize small Pacific nations in the south Pacific region:
In the post-Brexit era, the U.K. will be looking to make itself more valuable to its various partners. One area in which it already has a very deep bench is intelligence and strategic analysis. Two of the diplomatic missions the U.K. is reopening, in Tonga and Vanuatu, were only closed in 2006. There are people in the Foreign and Commonwealth Office and other circles with strong knowledge of the region and good contacts.
The U.K. also had existing representation in Fiji, Solomon Islands, and Papua New Guinea. With six posts in the South Pacific, the U.K. will have better coverage in the region than the U.S. (excluding its Freely Associated States), France, Germany, India, or just about anyone else except Australia, New Zealand, Japan, Taiwan, and China.
Britain could be a major factor in resisting Chinese penetration of the region that could harm the interests of America, Australia, and New Zealand, for example.
For that mission, the small British naval efforts that defy China in waters close to China would be excellent background scenery for British efforts to provide alternatives to China in the south Pacific region.
So while I noted (correctly) that the impact of the small British naval contribution on the China issue would be pretty small; the impact of British ships fresh from defying China sailing to the waters of small south Pacific island nations could be pretty big.
UPDATE: Britain's military really is eroding, despite the effort to punch above their weight.