Far be it from me to suggest that theatre isn’t up to the job of translating John le Carré’s genre-defining oeuvre, but there may be a good reason why David Eldridge’s adaptation of The Spy Who Came in from the Cold marks the first time a le Carré novel has been made into a play. That 1963 novel – in which a washed-out British agent becomes ever more deeply mired in a fiendish Cold War plot to ensnare a kingpin of East German intelligence – is a shivery masterpiece in disillusionment and the art of information withheld. Yet neither survive...