When Passengers Land At A Uk Airport Are They...

[sandyRoe]

... immediately entitled to the protection of British law?

I was thinking of the man who assassinated Martin Luther King.  He flew to England knowing he wouldn't be extradited back to the USA if he faced the death penalty.

If UK authorities knew he was coming and refused entry could he have been immediately sent back?

[barry1010]

Yes. They will not be extradited unless the Home Secretary receives written assurances that they will not be executed

[douglas9401]

Those assurances should be written by someone wearing a white hat rather than black.

This guarantees that the message is genuine and will be honoured. Many have been caught out by the various levels of US justice and their shenanigans.