McNee had commanded the second largest police force in Britain in Strathclyde and was now in charge of the largest. His lengthy experience as a low-ranking beat officer in Glasgow, however, was at odds with the academic and theoretical training he had received at Bramshill in the Senior Officers's course. Determined to improve the working conditions of London's beat bobbies, McNee implemented several reforms to the Metropolitan Police, some of which would be further refined by his successors.
One of the most dramatic incidents to occur during McNee's time with the Metropolitan Police was the siege of the Iranian Embassy in 1980. McNee and the Met were praised for their response and actions during the siege, however, when the first hostage was shot, McNee immediately handed control of the operation over to the British Army, who deployed the Special Air Service to storm the building and resolve the situation.
One of the most serious riots in London of the 20th century took place in Brixton over 10, 11 and 12 April 1981. The riot resulted in almost 300 police injuries and 45 members' of the public being injured; over a hundred vehicles were burned, including 56 police vehicles; almost 150 buildings were damaged, with thirty burned. There were 82 arrests. Reports suggested that up to 5,000 people were involved in the riot. McNee considered that it was unfair for the subsequent Scarman Inquiry into the riot to concentrate on policing and not extend in depth to the wider social, political and economic context. He believed the police were being set up as scapegoats for the riot. Initially McNee alleged the rioting was not spontaneous but organised outside the Brixton area by extremist left-wing militants, however, no evidence of a prior conspiracy to trigger the riot was uncovered by Lord Scarman. McNee was against the repeal of the sus law, believing that no evidence had been provided that arrests under that law did harm to the relationship between the police and black people. He did not believe pressure for repeal came from the law-abiding citizens of Brixton but instead from external extremists. He had earlier expressed his opinion that black people were disproportionately targeted by the sus law because there were indications that they were "over-represented in offences of robbery and other violent theft".
The investigation into corruption amongst City of London Police officers and Metropolitan Police officers known as Operation Countryman occurred predominantly during McNee's tenure. McNee was very critical of the conduct of the investigation, in particular that the investigation team would not pass him evidence relating to complaints made against his police officers.
Later life
McNee was knighted in 1978, and remained as Metropolitan Police Commissioner for five years until his retirement in 1982. He published his memoirs, McNee's Law, in 1983. McNee married Isabel Clayton Hopkins in 1952. They had one daughter. In his memoirs, McNee said of his wife: "During our marriage Isabel always put my needs as a police officer first. She has never failed me." Like her husband, she was a devout Christian, and was involved in several charitable endeavours. In her later years, Isabel suffered from various blood disorders, and she died of leukaemia in 1997. In 2002, aged 77, McNee married Lillian Campbell, 56, the widow of a close friend Norman Campbell who had died the previous year. McNee was an active freemason. McNee died unexpectedly at home in his 95th year.
