Kirkpatrick volunteered for active service on the outbreak of the First World War and was commissioned in November 1914 in the Royal Inniskilling Fusiliers.

Appointed Director of the Foreign Division of the Ministry of Information in April 1940, he became Controller of the European services of the BBC in October 1941.

One of the things that Kirkpatrick is most famous for during this time, was his January 1953 decision ordering the arrest of what he described as a "high-level cabal of neo-Nazis intent on undermining German democracy".

In his memoirs, Kirkpatrick later recalled his thoughts on taking up his new position: From my long years of previous service in the Foreign Office I knew what was in store for me and, like any athlete, went into training.

He joined the Office in February 1919 after spending the previous three years in wartime intelligence and propaganda work, an activity to which he returned when in 1941 he became foreign adviser to the BBC.

Convinced that the nation's survival was dependent upon the exercise of great power responsibilities, he encouraged the Prime Minister, Anthony Eden, in his dangerous fixation with Nasser as a Middle Eastern Hitler.

Kirkpatrick's closeness to Eden was reinforced by the Prime Minister's dissatisfaction with what he perceived as a pro-Arab stance held by his Foreign Office subordinates during the last Churchill administration.

This close relationship took an ominous turn when the PUS found himself obliged to exclude the Foreign Office from the decision-making process during the final crisis.

For Kirkpatrick, the Suez debacle was a test of Britain's great power status, leading him later to reflect that: No country [in the Western world] can any longer pursue an independent foreign policy.

The liberty of action of each is in varying degrees restricted by the need to obtain the concurrence of one or more members of the alliance.As Permanent Under-Secretary during the Suez Crisis Kirkpatrick was in favour of a strong line against Colonel Nasser.

In a letter to the British Ambassador on 10 September 1956, Kirkpatrick said: If we sit back while Nasser consolidates his position and gradually acquires control of the oil-bearing countries, he can and is, according to our information, resolved to wreck us.

[6] However, Suez sullied Kirkpatrick's reputation as PUS, though he may have been guilty of no more than fulfilling a civil servant's duty of loyalty to his political chiefs.