In MI6’s postmodern fortress HQ at Vauxhall Cross on London’s Embankment, Blaise Metreweli, the service’s new “C”, is settling in to an office vacated by her predecessor, Richard Moore. “All the Turkish stuff has gone,” says a colleague, missing the outgone chief’s propensity for Ottoman furnishings gathered when he was ambassador to Ankara from 2014 to 2017. “It feels very bare,” sighs another colleague. The new C will get to decorate her office in a style that might reflect her own eclectic background – a childhood in Hong Kong, postings in the Middle East including Iraq during the war –...