"Burgess", wrote Richard Norton-Taylor in The Guardian, "charming and often drunk, was a much more dangerous and effective spy than has been assumed.

"[2] The Times review commented: "He was also the most ruthless of the Soviet spies active in England before 1951, and every bit as destructive as Kim Philby.

"[4] Lownie's work demonstrated that, far from being the least important of the Cambridge Five, Burgess was perhaps the most interesting, most complicated, and most influential of the five.

The Daily Telegraph[6] Writing in the English Historical Review in October 2017, Matthew Hughes described Lownie's biography as a "labour-of-love [...], a cracking read, rich with archival detail and interviews with those who knew Burgess.

Lownie throws up three central questions: why did Burgess spy for the USSR, why did the British establishment not see him for what he was and how much damage did he do?