Jodie Foster's award speech at the Golden Globes made sardonic reference to celebrities being 'expected to honour the details of their private life with a press conference, a fragrance and a primetime reality show' Reuters

She was, of course, ready for her close-up. Deliciously groomed and styled by someone who seemingly doesn't hate women, Jodie Foster was fully prepared for the biggest soliloquy of her life. And yet, because she is an actor, the Oscar-winner began her speech accepting the Cecil B DeMille award at the Golden Globes yesterday by claiming spontaneity: "I have a sudden urge to say something that I've never been able to air in public."

This was not a sudden urge, a lightning reflex to pick lint off a loved one's coat. This, a sort-of coming out speech – she had paid tribute to "my beautiful Cydney" Bernard, her then partner, at a Hollywood breakfast in December 2007 – was 50 years in the making. Forty-seven of which she has been in front of cameras. And most of which she has been in what Out magazine called, on their notorious May 2007 cover, the "glass closet": on view but unacknowledged. Hiding, if you will, in plaid sight. Not waving, nor drowning.

The speech was glorious, gracious. It was funny. Following her "I'm just gonna put it out there loud and proud" build-up she snatched away the expected "I'm gay!" denouement with, "I am single. Yes I am. I am single." Laughter. Applause. The revered veteran with a blistering talent was starting to reveal her real self. This is as rare in Hollywood as egg yolks. It was also rather moving. Foster recalled coming out privately "in those very quaint days when a fragile young girl would open up to trusted friends and family and co-workers and then gradually, proudly to everyone who knew her."

And, probably, most viewers continued to be moved when she justified her decades of zip-lipped, keep-'em- guessing, identity-dodging by appealing for us to sympathise with her plight. "If you had been a public figure from the time that you were a toddler, if you'd had to fight for a life that felt real and honest and normal against all odds, then maybe you too might value privacy above all else."

I sympathised, vaguely. But I could not ignore the message forming in my head from a careers-worth of interviewees – from Jamaican lesbians "correctively" raped, from Cameroonian gay men tortured by police, from the mother of Matthew Shepard, murdered by homophobes and left tied up in a Wyoming field - the message bellowed out: you had choices. You could have left acting at a young age, already rich and cosseted, to live an authentic life. You could have had that privacy if it were that important to you. You could have come out, easing the way for others like you. Instead, you chose your career, and you lied by omission about your orientation. All of which leads us to two oft-uttered questions: why does whom one love/sleep with matter and whose business is it anyway?

At the beginning of Foster's career, in 1965, psychiatrists were still treating gay people with electro-convulsive therapy. Almost all lesbians and gay men were closeted, shamed into lives of a million lies, or driven to a desperate end on a train track. Only when a clutch of fearless drag queens fought back at police in 1969 at New York's Stonewall Inn did our lives being to change. And everything since then – every gay TV character, every gay politician, every persecutory law revoked, every last triumph or freedom we've ever enjoyed, has come from a single act of defiance, repeated tirelessly across the world: the act of coming out.

Without visibility we would have nothing. Without millions of ordinary people, kids in British state schools, activists in Uganda, married Christians in the Bible belt, saying, "Actually, I'm gay," Jodie Foster would not be able to stand up, resplendent, creaking open the closet door free of consequences. She surfed the wave of others' courage and gave back only when she felt like it.

It is every gay public figure's social responsibility to be out, to make life better for those without publicists and pilates teachers. Those who cry, "It's none of your business! Who cares who I sleep with?!" shirk their public duty, and deny the shame that keeps the closet door shut. Do straight people consider their orientation private? You cannot skip the tough part of a human rights struggle. I long for being gay to be nobody's business, to not matter, but we're a long way off. You either do your bit, and in the case of an A-list actor, that means blazing a trail for other performers, or you remain concealed, bleating about privacy.

Why do gay people, such as Ian McKellen, John Gielgud, and indeed Jodie Foster make such luminous actors? Perhaps because they get a lot of practice. We're all child actors. Some never stop. The only difference is Jodie Foster got paid for it.

• This article was commissioned following a suggestion by Timthemonkey. If there's a subject you'd like to see covered on Comment is free, please visit our You Tell Us page