First of all *["License to Kill"][1]* is a real thing rather than being completely fictional, although it has been made famous by James Bond franchise. According to Wikipedia:

> License to kill is the official sanction by a government or government
> agency to a particular operative or employee to initiate the use of
> lethal force in the delivery of their objectives, well known as a
> literary device used in espionage fiction. **The initiation of lethal
> force is in comparison to the use of lethal force in self-defense or
> the protection of life.**

Regarding your question *Is his immunity only binding for the justice system of the UK or are there any allies which also recognize his immunity?*

> The legitimacy of deadly force usage from country to country is
> generally controlled by statute law, particular and direct executive
> orders, the common law, or rules of engagement

Wikipedia also mentions about the part of James Bond franchise in popularising this concept

> The idea of a licence to kill is popularly **known from** the James Bond
> novels and films, where it is signified by the "00" (Double O)
> designation given to the agents in the series who are licenced to
> kill; Bond himself is famously agent 007.

More details can be read on the wikipedia entry.


  [1]: http://en.wikipedia.org/wiki/Licence_to_kill_(concept)