His new boss, Sir Henry Cuthbertson, a former military man who epitomises the haughty upper-class British imperialist, barely attempts to conceal his disdain for the under-educated agent who, although more and highly experienced, quite obviously does not stem from the "right class".

Next, the story unfolds around British and American attempts to facilitate a safe defection of high-ranking Soviet General Valery Kalenin, KGB Director of Operations for more than twenty years.

However, their joy is short-lived when Kalenin reveals that his "defection" was merely the bait in an elaborate trap to capture the heads of both MI5 and the CIA in order to exchange them for an important Russian agent currently imprisoned in England, and that his men are now in complete control of the safehouse.

The Russian agent is released and flies home to Moscow, while Cuthbertson and Ruttgers are presumably disgraced and dismissed from their positions, and Charlie and Edith, now in hiding in Brighton, celebrate their freedom with the money.

The New York Times wrote: "Directed crisply and cleverly by Jack Gold ... Charlie Muffin is a diverting spy adventure, complete with a genuine surprise ending.