Britain is a small country with a small navy. Compared to the USA.
On a world stage, though, their navy is quite formidable. They have 88 combat ships, compared to the USA with 450, but the USA is clearly the elephant in the room.
But England has other things that are hard to measure.
As an Island, they are protected by Europe’s landmass without being connected. This means they don’t need their navy to protect their shores. They have a long and storied naval history, brave men, very good pilots and highly competent officers. They also have a long history of being projected into hostile places a long way from home.
There are tens, perhaps hundreds of thousands of British citizens that spend their lives outside England.
In trade, he who protects the shipping lanes owns trade. Rome became an empire when Octavian defeated Marc Antony and took control of the red sea trade routes and the silk road.
In fact, England doesn’t need to protect the world, just Suez and the bad al-Mandeb. (The entrance to the Red Sea.) The already protect the Strait of Gibraltar.
From a purely geopolitical standpoint, China will never have a presence in the Mediterranean. It will take years, perhaps decades for them to control their own coastlines, if they ever accomplish that. They are surrounded by blood enemies in Vietnam, India and Taiwan.
Brexit breaks England from all their responsibilities on the continent and makes Europe their bastard son.
Even if Germany and France decide to build out their military, it would take years and cause unimaginable social strife. Even if they did, would you rely on France to protect you?
As I have mentioned before, Brexit returns England to its “island” status, much like it was when it first started to expand under Elizabeth 1st. Their Royal family gives them a natural tie to the middle eastern oil dictatorships and its strong cultural ties to India gives it an easy presence there.
In total, European countries rake in more than $250 billion in year in direct energy taxes and probably another $100 billion in indirect taxes. Rome got filthy rich taxing silk. England could get equally rich not only taxing oil, but having it trade in Pounds.
Brexit could work. The common Brit may not like it, but hey. They can always emigrate to South Florida and live in their summer homes.