There are few openly transsexual people in British public life -- and virtually none who have come out when already famous. The most notable exception remains acclaimed travel writer Jan Morris, who kept her gender reassignment secret until announcing its conclusion in 1972 and then publishing her autobiography, Conundrum. Since then, nobody approaching Morris's level of celebrity has publicly transitioned, with almost all of Britain's known transsexual people realising their identity before stepping into the spotlight.

By contrast, the hard work of post-war activists and the courage of openly gay, lesbian or bisexual people have created a climate where, slowly, public figures can discuss their sexual preferences without press intrusion -- or pressure to act as advocates -- ruining their lives. Since Thatcher's Conservatives passed the deplorable Section 28 in 1988, banning the "promotion" of homosexuality in schools, progress has been remarkable: having apologised for this legislation, David Cameron's government now retains 13 openly gay Tory MPs, and there is now a diverse range of visible gay, lesbian or bisexual people in the arts, media and, gradually, sport.

The situation for noted people in any field who come out, or are outed as transsexual would almost certainly be less accommodating. (I focus on 'transsexual' rather than 'transgender' people, cross-dressers or transvestites, as the 'Real Life Experience' required to access medical treatment obliges full time living in the chosen gender, making its public expression and resultant attention unavoidable). As there have been so few test cases, I can only speculate on what may unfold, but the experiences of visible transsexual people in the USA offer some clues.

Recently, at least three Americans have publicly transitioned: Cher and Sonny and Cher's son Chaz Bono, actor Alexis Arquette and LA Times sports writer Mike Penner, briefly known as Christine Daniels. Chaz Bono transitioned from female to male, Arquette and Penner from male to female; their contrasting fortunes, including Penner's detransition and suicide, illustrate the challenges that a British counterpart might face.

The fundamental issues would be around privacy. The concerns for anyone whose transition is picked up by the print or broadcast media have been covered here by David Allen Green, but for our transsexual pioneer, these would be magnified by already being in the public eye.

Interest would be most intense at the point of disclosure, which could mean facing virtually every consequent social challenge simultaneously. If preparing to come out, a transsexual person would be best served telling family, friends and colleagues before the press -- if secured, their support would be vital in dealing with inevitable 'curiosity'. If not, that person might think again about going public, although doing so would eventually become essential according to the gender reassignment pathway -- and once made, the announcement may find its way into the public domain anyway, even if retracted.

If outed by someone else, around the start of the process, that person would not have the reassurance that loved ones could be relied upon for backing -- and may have no idea who to ask for help. (Anyone who did come out today might seek out Trans Media Watch as a first point of contact, as they provide support to people whose gender status is widely known.) Either way, the Real Life Experience would have to begin at some point -- and the scrutiny of his or her appearance, if not entire life, would start.

"Before and after pictures have long been a staple in media coverage of transsexual people, alongside undermining of the identity chosen. This is not to mention the possibility of speculation about personal and professional relationships or mental health, or intimate questions about sexuality, genitalia and surgery -- something that activist Christine Burns, for example, had to manage in television appearances -- all when this person would feel most vulnerable, striving on several fronts to assert his or her true self.

For those with little connection to other similar people or any grounding in trans politics or theory, some challenges may come as an unpleasant surprise. Chaz Bono and Alexis Arquette both spent plenty of time within LGBT circles before transition and probably knew what types of attack, and what support, could reasonably be anticipated not just from "straight" conservatives, but from certain lesbian or gay critics, and the 'transgender' community (an increasingly fractious alliance, which, like many groups struggling for social change, has sometimes been susceptible to attacking its own). One of the saddest parts of Penner/Daniels's sad story, chronicled here by Steve Freiss, was the breakdown in relations with trans support networks over how Daniels presented as a woman, and how unprepared she was for this kind of criticism. The crucial problems, however, involved her relationships with her family -- not the media.

Given the continued lack of individuals who are able -- or allowed -- to offer a transsexual perspective to a large audience as a counterpoint to negative coverage, a public figure might feel pressure to 'represent' people, but this role could be declined relatively easily if he or she did not feel comfortable in assuming it. Bono and Arquette both became more famous as a consequence of transition, and have often seemed more comfortable performing an advocacy function, and their patient, articulate explanations of their histories and the support they have received from family, friends and the wider public bodes well for anyone in Britain who takes similar steps. But how much has changed here since Jan Morris's day still remains to be seen.

Juliet Jacques is the author of the Orwell Prize longlisted Guardian blog A Transgender Journey