Armistead Maupin speaks as he writes, in slow, short sentences that trickle from beneath his white moustache like honey on the turn: sweet but sharp. When he talks about the things that anger him - the Pope, for instance, or republicanism - his pitch doesn't rise, his voice doesn't quicken. In fact, it's when discussing what he perceives as the wrongs of the world that Maupin, chronicler of gay life and the first novelist to tackle Aids, seems most at ease.
Maupin's 10 novels all linger on themes of identity, sexuality, loss and the logical ("as opposed to biological") family. He is, of course, most famous for his Tales Of The City, which were first serialised in a San Francisco newspaper in the 1970s, growing into six volumes over the next 10 years. A mini-series (starring Laura Linney as token straight Mary Ann) was made in 1993, and a seventh book appeared 18 years later, in 2007.
Now an eighth volume - Mary Ann In Autumn - is out. It's a return to the heartbreaking and rickety world of Barbary Lane (or thereabouts) and a return, the critics are saying, to his 70s best.
While Maupin's books have always featured soapy storylines - secret identities, strange religious sects, amnesia - these bubble in a basin of such delicate writing and beautifully flawed characters that for his many readers (one of whom, upon discovering his name was an anagram for "Is a man I dreamt up", wrote to him questioning his very existence) his novels are more like bibles. At a reading recently, a fan told him that when her best friend died, he'd been buried with Maupin's books.
Despite its ties to the 1970s and 1980s, the legacy of Tales Of The City continues to grow. The day we meet, the Pope has condoned condom use for the prevention of sexually transmitted disease.
I ask Maupin how he feels about this inching forward of morals, and he scoffs. "The Pope's barbarism is so enormous that all he could do is quit to impress me at this point, so deeply mired in hypocrisy, in bad thinking. I have very little patience for organised religion, which is mostly dedicated to demonising homosexuality," he says. "That shows you right there how little they know about the nature of love, and true spirituality."
Maupin (one-time lover of Rock Hudson, who appears in his novels as a closeted film star) got married in 2007 to Christopher Turner, the editor of a website he'd been browsing, Daddyhunt.com. At their wedding, Laura Linney, to whom his new book is dedicated, read a poem - The Bliss Of With. At her wedding some months later, Maupin returned the favour. "The last line is 'You are my undoing and my altogether'," he says. "It's about the way someone takes you apart then puts you back together again. It was the loveliest way for Laura and me to be bonded forever."
"Forever" is a theme he returns to often. Despite having served in Vietnam, Maupin's war, he says, has been with Aids. "I'm distressed to realise that now there are gay men who've lost their sense of self-worth to the degree that they experience a sense of relief when they're infected," he says, "because they think there's nothing else left to worry about. But of course, that's really when the worrying starts."
The worry, he says, of a "forever" on medication. "People my age end up looking 90 after a lifetime on meds. But at least it is a lifetime now, if not an eternity."
Maupin has fallen happily into the role of international spokesperson for gay rights, but, at 66, is unafraid to veer endearingly off-message. In More Tales Of The City, his second novel, Michael Tolliver (the character Maupin based most clearly on himself) writes a coming-out letter to his mother, a letter that's been used as a template by real people countless times since. Referring to this, Maupin explains why he hasn't lent his name to the "It Gets Better" campaign for bullied gay teens in America, a video project whose contributors include Barack Obama and Jake Shears from Scissor Sisters.
"My work has basically been saying it gets better for the last 36 years," he sighs. "I'd be surprised if the suicide rates [that inspired the video campaign] have really increased - the sad truth is that gay kids have been killing themselves for years, and it simply hasn't been reported because of their families' shame. But the thing that is quite revolutionary [is that the campaign] is calling upon adults to defend children. For years adult gay folks had been wary of concerning themselves with the plight of gay teenagers for fear of being accused of seducing them. But we're the experts. At least now people are willing to talk about the bullying - that's an improvement."
However many decades pass, this will always be the story that Maupin tells, one of marginalised people fighting for a voice. "On the other hand, when I was a child, homosexuality wasn't a constant topic of discussion," he adds. "Now it's everywhere. Even though back then there was great darkness around the subject, the pressure for young people now is greater. It gets better, sure, but it gets worse, too."
Mary Ann In Autumn (Doubleday $38.99, out now).