Spy story

How fifth Cambridge Spy beat the courts: John Cairncross escaped prosecution because his brother was government's top economic advisor

The fifth Cambridge spy was spared prosecution because his brother was the Government's chief economic adviser, newly-declassified files reveal.

John Cairncross is believed to have passed atomic secrets to his Russian handlers during the Cold War, causing immense damage.

Files reveal that British officials decided not to pursue a prosecution against the Communist spy after he secretly confessed.

They feared they did not have enough evidence, but they also worried damaging headlines would embarrass his brother.

The Government's chief economic adviser at the time was Alec Cairncross who had never come under official suspicion.

Yet officials feared that his reputation would be damaged if revelations his brother was a spy became public.

In a note to prime minister Sir Alec Douglas-Home, cabinet secretary Sir Burke Trend wrote: 'Quite apart from the distress and embarrassment which this would inflict on an individual whose integrity we have no reason to question, we have to ask ourselves what would be the probable result, in terms of public policy in the widest sense, if it became known that the government were employing, as their chief economic adviser, a man who is the brother of a self-confessed Communist spy.