Lawyers for the UK government had argued that the case should not proceed as "a finding by our court that the notional UK operator of a drone bomb which caused a death was guilty of murder would inevitably be understood … by the US as a condemnation of the US."

Responding to the ruling, Kat Craig, legal director of the human rights charity Reprieve, which is supporting Khan, said: "It is shameful that the risk of embarrassing the US has trumped British justice in this case.

"It now appears that the UK government can get away with murder, provided it is committed alongside an ally who may be sensitive to public criticism. It is a sad day when the rights of civilian victims of drone strikes take second place to the PR concerns of the US government."

"However, I am still determined to get answers from the UK government about the part they have played in the death of my father. The CIA's drone programme has not only killed hundreds of civilians, but is turning people in Pakistan against the US and its allies.