On 13 August 1953, Nott-Bower was appointed Commissioner. Although he had been a popular and energetic Assistant and Deputy Commissioner, he was regarded as a somewhat lacklustre Commissioner. In his 1955 book
Against the Law,
Peter Wildeblood quotes an article written by
Donald Horne for the
Sydney Morning Telegraph printed on 25 October 1953 referring to Nott-Bower's role in the 'Great Purge' . "The plan originated under strong United States advice to Britain to weed out homosexuals – as hopeless security risks – from important Government jobs. One of the Yard's top-rankers, Commander E. A. Cole, recently spent three months in America consulting with FBI officials in putting finishing touches to the plan. But the plan was extended as a war on all vice when Sir John Nott-Bower took over as the new Commissioner at Scotland Yard in August. Sir John swore he would rip the cover off all London's filth spots.... Under laxer police methods before the US-inspired plan began, and before Sir John moved into the top job at the Yard as a man with a mission,
Montagu and his film-director friend Kenneth Hume might never have been charged with grave offences against Boy Scouts.... Sir John swung into action on a nationwide scale. He enlisted the support of local police throughout England to step up the number of arrests for homosexual offences. For many years past the police had turned a blind eye to male vice. They made arrests only when definite complaints were made from innocent people, or where homosexuality had encourages other crimes. They knew the names of thousands of perverts – many of high social position and some world famous – but they took no action. Now, meeting Sir John's demands, they are making it a priority job to increase the number of arrests.... The Special Branch began compiling a "Black Book" of known perverts in influential Government jobs after the disappearance of the diplomats Donald Maclean and
Guy Burgess, who were known to have pervert associates. Now comes the difficult task of side-tracking these men into less important jobs – or putting them behind bars." He introduced few reforms or innovations. He did set up the Research and Planning Branch and the Metropolitan and Provincial
Regional Crime Squad and centralised traffic control in response to rising private car ownership. He did little to combat the rising crime rate, however; he refused to address the outdated hardline attitudes of many senior
detectives, which were becoming increasingly out of step with postwar society; and he did not support his men in their claims for better pay and conditions. Police pay fell rapidly below
inflation and rates of pay in the private sector. This caused recruiting problems and the force became seriously under strength. Nott-Bower was regarded by many of his officers as a pleasant but ineffectual man. He retired in August 1958 and Chairman of the
fire alarm manufacturer Auto Call Company in April 1960. ==Honours==