Almost two years after the death of Jan Morris, the jaunty travel writer and pioneer of modern gender transition, her first post-humous biography has arrived. (I follow Paul Clements in using the feminine pronoun throughout.) It is lively and well written, but it’s not the finished product. It lacks access to the private papers of its subject and her wife Elizabeth. That extra layer of insight into a fascinating but elusive personality must doubtless await the authorised life by Sara Wheeler.

In the meantime, Clements deserves plaudits. He has worked his personal knowledge and existing sources well. We learn more than before about Morris’s modest if comfortable upbringing, with Welshness on the paternal side; education at Lancing and Christ Church, Oxford; a character-building spell at Sandhurst; and about her talented, musical brothers. One of them played the flute at Elizabeth II’s coronation – the event neatly heralded by the conquest of Everest, which Morris announced to the world in a coded message dispatched down the mountain via a Sherpa.

By then she was prospering in journalism, initially at the Times, and subsequently, when not allowed to combine reporting with writing books, at the Guardian, when a major scoop about western collusion over Suez helped change the course of British history – or so Clements ambitiously claims. Both outlets allowed her to travel to distant parts of the retreating British Empire. At this remove, her book on Oman somehow sounds more engaging than some of her later effusive offerings on bustling cities and countries. She managed to annoy the sultan by referring to the remnants of slavery. Her desert sorties also antagonised the old-school explorer Wilfred Thesiger, who dismissed her work as ‘chatty rubbish’, and led to one of the few personal feuds engaged in by someone who made kindness a life principle.

In those days Morris could still be abrasive about destinations. She irritated Australians by describing Sydney as ‘aloof’ and materialistic, and found Washington DC ‘perhaps the most ineffably boring city on the planet’. Such trips helped her accumulate material for Pax Britannica, the acclaimed 1970s trilogy on the Empire – a historical phenomenon she admired more for its trappings than its day-to-day operation.

Then came the transition, the event which defined her life. She had long seen herself as a woman in a man’s body, and the disparity became too painful. Clements carefully puts the medical and psychological details into historical context and assesses the reactions to her subsequent book, Conundrum (1974). Critics, from Germaine Greer to radical lesbians, have accused Morris of adopting a persona that was a parody of the female stereotype other feminists were trying to discard. A debate endures on whether her own writing altered in any way.

Thereafter, she became a celebrity, with American magazines competing for her services. Her favourite outlet was Rolling Stone, which gave her considerable space, its West Coast hippy roots reflecting her own sense of adventure and anti-authoritarianism. Notably prolific, producing 3,000 words daily (including playful favourites such as ‘flibberti-gibbet’), she published 58 books, most of them capably chronicled by Clements from gestation to critical reaction.

Her other major departure was the rediscovery of her Welshness. Having started marriage on a houseboat in Cairo, and then lived in Oxford and Bath, she moved with Elizabeth and their four children to Gwynedd in north Wales, where she found a culture both romantic and apparently peace-loving, in parallel with her new gender. She became more avowedly republican, a stance slightly contradicted when she accepted a CBE. But, always brave and opinionated, she also railed publicly against the Welsh first minister Rhodri Morgan for his lacklustre response to devolution – an attitude which led to an unexpectedly negative backlash, including being sent a hoax anthrax package.

By this time Morris was burnishing her image as a charming, super-sharp ‘aunty’, though she probably wasn’t thrilled by Jonathan Raban comparing her to the eponymous Tootsie of Dustin Hoffman’s 1982 film. But there was another side, which Clements can’t get to grips with. He touches on it when he quotes Morris’s daughter Suki: ‘Jan was a really complicated person, not, in my view, the simple lovely being that people see at all.’

He might have explored this further, but has lacked access to Morris’s personal letters and diaries. So there is nothing particularly revealing, for example, about the family tensions her globe-trotting or transition caused. An ‘open marriage’ is mentioned, but details are obscure. Elizabeth is generally portrayed as benevolent, though at one stage she assails her spouse with a saucepan; at another, Jan admits undue anger when Elizabeth shows signs of dementia.

So it wasn’t all plain sailing. Clements sums up his subject, not entirely convincingly, as in continuous flight – from family, country and gender. Whatever the metaphor, Jan Morris’s extraordinary journey is still being retrospectively charted.