I can well understand that joy and relief experienced by the supporters and families of the hostages released yesterday by Vladimir Putin. For I myself owe my life to a Cold War spy swap.

In October 1969, the British government exchanged Peter and Helen Kroger, two senior Soviet career spies nabbed for running a very real espionage ring, for Gerald Brooke, a British student who had served five years in a Russian jail for ‘anti-Soviet agitation’.