Tom Holland is already waiting by JRR Tolkien’s grave when I arrive at the Wolvercote Cemetery in Oxford. Leggy, languid, splayed across a bench with a book, wearing a worker jacket and paisley shirt, Holland is a postcard of English erudition. “Such a brilliant place for a rendezvous,” he grins with trademark enthusiasm.

We linger for a while, exchanging small talk about the Roman conquest of Judea, and eventually Dominic Sandbrook barrels up. Short, stocky, bluff — hobbit-like? — Sandbrook is wearing a suit, braces and Richard Nixon-themed cufflinks, as befits his budding transatlantic power historian status.