I thought I had read this once before but I didn't remember anything except the name of the pilot "Tiny Ricardo".
Le Carre has two sides, the guy who wrote "Tinker, Tailor,..." and a hack best-seller writer. This has to be classed in the hack department. There's plenty of the standard devices of characterisation, suspense, and throw away sex and violence.
Whereas the complexity of TTSS was taut and is integral to the novel the complexity in this one feels contrived. The ending was also excessively drawn out I thought, and Westerby's motivations seemed quite insufficient for his actions.