Can Britain revoke the independence of a former colony? [closed]

In theory, pass a law saying they're no longer independent. Afterwards the country which just got their independence revoked will have a good laugh, tell them to get lost, and possibly launch some sort of diplomatic sanctions.

If the country passing the law tries to actually make good on it, expect most other countries in the world to tell them to get lost as well.

Practically speaking, independence isn't something you can really revoke, barring military invasion. After all, by making a country independent you're implicitly letting go of your claim on them.

The UK and certain other countries in the Commonwealth are a bit of a special case, since they still have the British king as their nominal head of state (as noted by @Steve Melnikoff in the comments, not all Commonwealth countries do though). I imagine it still wouldn't work though, and would probably just end with the country in question leaving the Commonwealth. Though this doesn't really apply to the USA, since they were never part of of the Commonwealth (as noted by @Emil Jeřábek), and rather famously (and somewhat violently) rejected the British Monarch during their war of independence.

In the end, the UK and USA are separate, independent countries, and the UK has no legal power to revoke said independence. The only way to force that issue would be outright war, and I'm pretty sure everyone knows who'd win that one.

In the Westminster legal system, what is the correct procedure for revoking the independence of a former colony which is unable to govern?

First of all, most colonies became independent, because Britain was unable to govern. More precisely, the financial, human and political expense of holding onto colonies outweighed their usefulness.

Secondly, we also have to be careful about what we mean by "colony" - various protectorates, mandates, concessions, and treaties of special relationship are just euphemisms for "colony", palatable to western public, but often viewed as colonizing by the peoples concerned. Lords of the Desert: The Battle Between the United States and Great Britain for Supremacy in the Modern Middle East is an excellent and accessible account of how Britain was squeezed out of its possessions in the Middle East, although Palestine, Egypt, Iran and Yemen are probably not what the OP meant by colonies.

The examples given above allow to point out several obstacles to reclaiming a colony:

• It is still too costly, and presents too few advantages
• When a colony became an independent state, such a reclamation would constitute a violation of this state' sovereignty (aka aggression.)
• The stronger independent states would resist - politically and militarily.
• The weaker ones are "protected" by another power - most likely US, Russia or China, so there will be opposition from this power.
• Finally, there may be colonies that are still de facto controlled by Britain, despite their officially independent status - if this works, what's the point of reclaiming them?

For purely legal aspect it is probably better to inquire in teh Law community.