When it comes to unpacking John le Carré’s career as the pre-eminent spy writer of his generation, what better place to start than with a piece of luggage? One of the most moving artifacts on display in “John le Carré: Tradecraft,” from the Weston Library here, is a silk-lined, white-hide suitcase from Harrods embossed with the initials OMC. Le Carré, who died at age 89 in 2020, recounts in his autobiography “The Pigeon Tunnel” how he discovered the case in his mother Olive’s home shortly after her death in 1989. It was, he writes, the only thing left “which bore witness to her first marriage,” after she fled the family home when David Cornwell—the future John le Carré—was 5 years old, leaving him and his elder brother in the care of their father, Ronnie Cornwell, a notorious conman (and subsequent literary inspiration) whose criminal exploits had made domestic life untenable.