In the past week a British Family Court judge summed up a case involving a transgender man in this way: “modern life can be complicated”. Mr Justice — I am putting aside for a moment your wig and your dress — you could not be more right.

We are fresh from the unveiling of Caitlyn Jenner on the cover ofVanity Fair. Rocking a high-glamour bodice, Jenner is a 65-year-old transwoman, formerly known as Bruce, also an American Olympic decathlete, Christian, Republican and reality TV star. Jenner has her British equivalent: in April our highest-profile boxing promoter returned to work as Kellie Maloney. Kellie, now appearing ringside as a stylish 61-year-old with long blonde hair, said how unexpected she found the support from boxers who knew her as Frank: “I was surprised, if I’m being honest, it was overwhelming.” But if boxers are fine with transgender, a surprising group have come out fighting — women who will not accept transwomen as their own. As I spoke to trans people and their critics I realised “complicated” is in fact, an understatement.

The acronym “LGBT” (Lesbian Gay Bisexual Transexual) charts, in order of initials, a history of acceptance: from Victorian times the British were pretty cool about lesbians, mostly because we didn’t believe in them. Then came the bruising gay rights campaigns of the 1970s and 1980s. But what’s this “T” that has come late to the party? The rights of transgender people were enacted in the UK in 2004, but it is a decade on that more trans people feel able to make their public debuts. The new series of Orange Is the New Black airs on Friday starring Laverne Cox, the first transgender actor nominated for an Emmy. The BBC is filming Boy Meets Girl, a sitcom which is the first to have a transgender actor as its star. It follows a romance between a man and a 40-year-old transwoman, who is played by a transwoman actor Rebecca Root.

It feels now, people said to me, like coming out as gay did 20 years ago: on the edge of changing social mores. Your friend may be relaxed about it, but your Aunt Edna would be appalled (apologies Aunt Edna, I know you mean well). The rest of us — steeped in the use of gender swap as a comic device, from Shakespeare on — struggle to strike the modern tone. As Richard Friedman, an eminent psychiatrist in the field, joked, “it might help if they all wore T-shirts that said, ‘don’t worry, it won’t happen to you’ ”.

Now this article could be a simple guide to “how to react to the transgender in your life”, and Lord knows I need it. I used “tranny” in an article recently, with what I thought was affection, but now I know that too many have been beaten up by those shouting “tranny” for this to be polite. And for those at the back of the class, yes there is a difference between a transvestite and transgender. As different as drag queen Lily Savage is to Jan Morris, the legendary Times reporter turned author, who “transitioned” in 1972 and has lived as a woman ever since, becoming “sick to death” of being asked about it. “I do not doubt,” Morris has mused, “that when I go the event will be commemorated with the headline: ‘Sex Change Author Dies’.”

But transgender people face a coalition opposition. It isn’t the simple case of gay people versus social and religious conservatives. The Jenner photoshoot was applauded by young feminists on the Jezebel site, and by The Times’s own Caitlin Moran, who was asked at theGlamour awards this week about her namesake, and, in summary, said, “power to you lady!” But The New York Times carried a much-read opinion piece from a former professor of women’s studies who wrote, “they cannot stake their claim to dignity as transgender people by trampling on mine as a woman”. Alice Eve, the British actress, tweeted about Jenner: “Do you have a vagina? Are you paid less than men? Then, my friend, you are a woman.” Eve later retracted her comment, saying she “felt confused”. Not at all confused was Julie Burchill, who unleashed a hatestorm on Jenner: transgender was “extreme selfishness . . . and certainly not brave”.

If you think of transgender as an immigration issue, with genetic females as natives, this brand of feminism becomes a kind of Ukip. It takes something pretty special to marry the hard right and veterans of the 1970s feminist movement, but here it is. As a New Yorker piece on the battle put it, these old school feminists are “shunned as reactionaries on the wrong side of a sexual-rights issue. It is, to them, a baffling political inversion.”

I know Burchill is wrong on at least one count: bravery. I saw Katherine O’Donnell, night editor of The Times in Scotland, when she first walked into the Times newsroom as a woman. This was Fleet Street a decade ago, not the vanguard of social niceties. It was one of the bravest acts I’ve seen in my life.

But it wasn’t until talking to O’Donnell for this article that I realised its true cost. She knew from a very young age, “I wasn’t a boy. People are born trans, that’s what we are. No one wakes up and thinks it would be brilliant to be trans. It’s hideously costly for trans people to be in the public eye, we’re considered fair game.”

She was what Jan Morris described as a “silent prisoner”. Research by Brunel University found that nearly half of trans people age 16-26 had attempted suicide, compared to 6 per cent of the same age of the rest of the population. By the time O’Donnell was married and had kids, “it came to a point where I thought I can’t continue any longer to be a useful human being. It was either transition or pack up and die.”

Was it as difficult as she feared, I asked, expecting the answer to be no.

“Yes it was. It cost me my marriage, it cost me my brother. I have close friends who cut me out of their life completely. That’s a common story for trans people but things are getting better.”

She’s pretty tolerant of people, for example her mother, who at first got “he” and “she” mixed up (her mother is flawless now), just as Jim Naughtie got some flak for referring to Jenner as “he/she” on theToday programme.

“People wanting to get it right is different from deliberately misgendering someone. That’s saying, ‘aha, you can’t fool me mate’. Which is of course what transwomen very often hear before someone beats the s*** out of her.”

Transpeople are a small, ill-measured group: a paper from the Williams Institute in America estimated 0.3 per cent of the population. But the feminists in opposition are smaller still, as O’Donnell said, “a tiny group of people who are extraordinarily vocal . . . Overall the best reaction from everyone, the majority of people, was to say, ‘Oh, that’s fine, let’s get on and have a life’. My children have been wonderful.”

Let’s cut then to Cathy Brennan, an American lawyer who campaigns against the erosion of “sex-based” legal protection for women. In practical terms this means trying to keep women’s prisons, refuges, toilets and so on, free from potentially threatening male genitals. She says she has received death threats for her views.

“I am one of the few women in the world who are willing to say out loud that transwomen are men,” Brennan told me. “People are unwilling to engage in fair debate. I’ve got thousands of messages from people saying, ‘I agree with you but I wouldn’t say it out loud’.”

Only the other week the Daily Mail reported that a transwoman was refused entry to a Primark changing room, because she didn’t “pass” enough as a woman. But the surprising thing to me was that the comments online were so supportive of the transwoman: all no-nonsense, “they’re cubicles aren’t they? What’s the fuss about?”

I tell Brennan I respect the logic of her argument, but it feels uncharitable.

“I have personal empathy for transgender people,” says Brennan. “And I fully support their rights, such as for housing and jobs. But I think it’s wrong to pretend biology doesn’t exist. I think it’s uncharitable to put women in a position where they can be assaulted by men pretending to be women. No one cares about those women.”

Paris Lees is a presenter and journalist who thinks we have moved on from this. It occurs to me that as a transwoman in her mid-20s, Lees is part of a younger generation that just can’t see the big deal in the way older people do.

“I think those [feminist critics] are the old dinosaurs. Younger feminists don’t hold much weight with it. The majority find it really odd. I mean, in response to Alice Eve: so transwomen don’t know what it’s like to be objectified, raped, or underpaid?

“It comes across as mean: ‘you don’t belong in our woman’s club’. To me, it’s no different from walking down the street and someone shouting, ‘you’re a bloke aren’t you?’ It’s pure bigotry. Nasty.

“But the world changed for gay people between the 1970s and the 1990s, and it really is happening now for trans. We get punched by the same people. I was bullied at school for being girly, and bullied at home by my dad for not being the son he wanted. I couldn’t see a trans person reading the news or being taken seriously.”

Now, I feel as a society we’re confident in our reactions when people come out as gay. Lees believes that will happen for transpeople. I ask for her best advice for people who know someone coming out as trans, and she thinks for a minute. Then her answer puts the whole complicated mess into perspective. It really is quite simple, she says.

“If you care about a person, just love them. All the rest is just noise.”

Recording of Helen Rumblelow interviewing Cathy Brennan June 8, 2015: