A (largely negative) review in the Times notes:
'Boysie Oakes is another innocent involved in espionage: he is given a license to kill by British Intelligence, but as he would not hurt a fly himself he has to hire a professional killer to do the job for him. Then he gets involved in an elaborate double-bluff involving an assassination attempt on the Duke of Edinburgh as a cover for something quite different'.
Source:
'Perfect Ealing Subject–From Hollywood', The Times, 25 August 1966, p.6.