He notes what Taylor and Queen Elizabeth II had in common: “They were women set apart from what the rest of us think of as reality (bills, queues, pension plans, practical inconveniences, manila envelopes) for the entirety of their lives … their every public moment, every entrance, every exit, captured by cameras and newsreels. And yet no-one knows what they were really like – not even themselves.”

Lewis contrasts Burton’s Old Vic-style, declamatory diction to Marlon Brando’s Method mumbling, his screen persona to that of Peter O’Toole, Cary Grant, Kenneth More and many others. He situates Taylor in the tradition of the heroines of 19th century fiction, places her very public angst alongside Sylvia Plath’s, and reflects on her screen presence in contrast to Marilyn Monroe’s and Katharine Hepburn’s.

He shrouds their lives with the astonishing hedonism that characterised their existence – the excess of jewellery, clothes, planes, properties, servants, pets, in no particular order – and wields their almost Trumpian flirtations with despots around the globe as clear evidence of their detachment from reality. But while he specifies their many flaws as human beings (including Burton’s abandonment of his autistic daughter, Jessica, and the possibility that he was responsible for the death of his brother, Ifor, which Lewis spells as Ivor), he refuses to extract any straightforward narrative from their histories.

As my wife will attest, he’s often laugh-out-loud funny (“I thought you were working”). Without ever compromising the gravity of his project – a serious study of the fate that befell these two “fools of fortune”, or that they brought upon themselves – he suggests that there is something farcical, and essentially comic, about the world’s preoccupation with their escapades, real or imagined, about Burton’s unrelenting, self-important sufferings, and about Taylor’s extensive history of undiagnosed afflictions.

Lewis’ droll sense of humour pervades the book. During his cataloguing of their time in Italy, he wryly recounts the events of March 10, 1961: “Taylor has recovered sufficiently to entertain John Wayne, Tennessee Williams and Truman Capote at her bedside, although I don’t know whether all at the same time. Tom Stoppard ought to imagine it in one of his little plays.”

Appreciating that Burton and Taylor can now only ever be “ghosts glimpsed in mirrors”, Lewis makes no claims to truth-telling and refuses to sit in judgment. In fact, despite it all, he writes, “I absolutely refuse to disapprove of them”. Craftily having it both ways, he abhors their hedonism but also applauds it as a form of rebellion against the conservative mores of their time.

Erotic Vagrancy is a seriously exciting book, exuberantly written, intensely interesting. Furthermore, if I, too, can be permitted to have it both ways, it’s extremely exhausting, not to be read in a single sitting and even quite demanding over the most enjoyable week I spent with it.

The Booklist is a weekly newsletter for book lovers from books editor Jason Steger. Get it delivered every Friday.