Zan barely can bring himself to return J. Willkie Brown’s phone calls or overcome what petty satisfaction lies in making the other man call first. When they meet at a bookstore near Montague and Great Russell Street, sipping cold coffee drinks — the new London seems to have more coffee than tea now — on the afternoon of the family’s fifth day in the city, Zan spends most of the first few minutes fretting over whether the young woman behind the counter neglected to decaffeinate Sheba’s mocha. Maybe decaffeinated coffee, he worries, is one of those notions that Europeans find oxymoronic to the point of senseless.