Pamela Anderson is surprisingly proper. It’s not just her clothes - gingham top, pencil skirt, ballet pumps - but her careful choice of words, regal posture and finishing school manners (she pours her tea with a delicate flick of the wrist and won’t touch her food while talking) that seem more First Lady than Playboy playmate. So it’s a mark of quite how “awful” she finds trophy hunters like Donald Trump’s sons that she not only grimaces at their mention, but declares in that buttery, breathy drawl: “Anyone who does that must have a small penis.”

I’ve met Anderson at The Dorchester. She’s yet to have breakfast but already has a full face of make-up. But the actress - the Marilyn Monroe of the 90s, star of Baywatch and staple of boys’ bedroom walls - has long since recast herself as a pneumatic St Francis of Assisi. A long-term supporter of PETA, now focusing on conservation too.

Raising awareness isn’t enough - Anderson, who is chair of the ocean wildlife charity Sea Shepherd and on the Russian council of the International Fund for Animal Welfare, believes in action and wants to make activists of us all. Recently, she tried to buy beluga whales and orcas in Russia (for $20,000 each) that were set to be sold to a Georgian aquarium. She’s also going to Canada during the seal hunt, aping Brigitte Bardot 40 years ago. “I’m going onto the ice floes to take pictures with seals. [Canadians] get spitting mad when you start talking about it.”

Her recent lobbying of Russia on conservation issues has been controversial. “I don’t want to accept the propaganda we’re being force-fed about Russia in America,” she responds. “The Russians have relationships that America doesn’t, like with China. Sometimes people don’t want to be told what to do by the West.”

In December, Anderson’s going to Moscow. “I’ve fallen in love with Russia. In a crazy way [because] Putin is a very powerful man, he can be the hero. He loves wildlife. I know it’s basically a dictatorship, and he’s for all sorts of things I don’t agree with, but it needs someone as powerful as that to do something.” She notes that Putin does listen: “He stopped importing seal products because I wrote a letter to him.”

Anderson has had an affinity with animals since childhood. Feral cats would follow her; one, she recalls, walked sideways. She has spoken in the past about being sexually abused, and tells me that there were experiences that made her feel “animals were my only friends”. Until she had her two sons, Brandon (20) and Dylan (18), she preferred animals to humans.

Her animal activist awakening came aged six when she stopped her father hunting. “My Dad told me never to go in to the pumphouse, so I gathered all my girlfriends — ‘let’s just see what’s in there’. I found a deer carcass with no head, dripping into a bucket of blood. We all screamed. It was like a movie, pigtails flying everywhere” Her parents still eat meat “though less of it. I’ve tried everything.” When Baywatch made her famous, she called PETA: “I needed to share this attention with something meaningful. I was sick of talking about my boyfriends and my boobs.”

At this point, Anderson’s breakfast arrives. She has ordered a vegan Full English with more excitement than I've ever seen anyone muster about baked beans. The waiter had asked how she wanted her eggs. “It’s vegan — no eggs,” she sighed, a conversation she’s clearly had many times. She’s currently producing a film with James Cameron about vegan men, to show it isn’t intrinsic to masculinity to eat meat. “They’re showing Navy seals, body builders. Being vegan is actually more manly, because you are taking care of all of us. That's why men are on the planet: to protect and provide.”

This leads us onto a famous vegan sandwich: the Pret one she delivered to Julian Assange at the Ecuadorian embassy. Afterwards, there were false reports on Twitter that Assange was ill, and then wild rumours that Anderson had poisoned him. “There was no arsenic in the sandwich,” she laughs. “Who am I, 007? Julian didn’t even eat the whole sandwich.”

She considers Assange both a “political prisoner” and a friend. “I believe he’s one of the leaders of the free world. He’s sacrificed his life for us. Hopefully he will inspire people not to be corrupt.”

She was introduced to Assange by her close friend, Vivienne Westwood. “I’ll probably see him again before I leave. I adore him; he educates me. But there are elaborate plots against him. Even me visiting made me a target — people were saying things to discredit me.”

What does she make of the sexual assault accusations against him? “I think they’re completely false. it’s bullying on a different level.”

Anderson seems to collect causes. Her latest — working with Rabbi Shmuley Boteach — is calling for a “sensual revolution” (also the title of a book she’s writing). She worries hardcore pornography is “damaging intimate relationships, dehumanising” its users: “The sexual revolution had its good points but it also gave us really bad sex.”

Anderson was on Playboy’s cover 14 times and keeps saying she isn’t sure she’s entitled to criticise pornography. I tell her I disagree - that that gives her authority - and a mischievous grin spreads across her face. “I know, but I like it when other people say it. If I disqualify myself, everyone says ‘oh no, you’re the best’. It’s psychology.”

She thinks Playboy is different, anyway; it was “titillating, innocent” but hardcore porn is more damaging. “I’m concerned the world is going to forget how to make love. Viagra is going crazy, because people can’t get aroused by their wives any more. Women have said to me, ‘my husband hasn’t touched me in four years, because he’s in the basement watching porn’. It’s an addiction.”

This campaign was partly inspired by her sons, who she heard chatting to their friends about hooking up. “I said ‘If you disrespect women, you disrespect me. That’s not what love looks like. You have to be in a monogamous relationship to have a sexual experience.’ And they’re like ‘woah! Ok!’”

She’s mostly doing this for women, though. Women think they want to be treated like a sex symbol in bed. As an actual sex symbol, she disagrees. “I’m a romantic. I’ve been in experiences where I’m with a man I love and all of a sudden, he’s flipping me around, slapping me, spitting on me, calling me a whore.” She shudders. “What the hell? This is terrible sex! Get an imagination and call me back afterwards.” Shmuley has said that if Anderson is having bad sex, that’s the sign of the Apocalypse. Anderson smiles. “Even I can’t make love to a brick wall.”

Anderson has been married four times — to drummer Tommy Lee, to Kid Rock and twice to producer Rick Salomon — but she still believes in monogamy: “I look at my parents and think, ‘thank God they’re still together’.”

Though she admits her brain is struggling with so many different messages, she believes it’s all connected - porn, politics and conservation. “Desensitised pepople have a lack of empathy. If we don’t have empathy for each other, how do we have empathy for animals?”

Someone who seems devoid of empathy, Anderson notes, is Donald Trump. She met him once. “I think it had something to do with beauty contests. There were a lot of beautiful girls there. That in itself shows you [something]: what was he involved in that for? He says he loves women more than anybody — yeah, but for the wrong reasons.”

She didn’t see a lecherous side — he was with his wife — but isn’t surprised by the recent revelations. “He acts like a spoiled, rich brat who’s never had any repercussions for anything. He’s delusional.”

Although she’s a Bernie Sanders fan, Anderson will vote for Clinton. Will we see an explosion of misogyny if she wins? “The universe is bringing it up for a reason: we need to face it. Whenever a woman is taking a ‘man’s job’” — she makes air quotes — “it gets ugly.”

Ageing clearly agrees with Anderson. She says her eyesight’s going — she can’t read the menu — but that now people take her seriously. I say that’s there’s a gravity - meaning to say gravitas - that comes from getting older. “Oh, there’s gravity all right! I thought maybe if I sleep upside down in gravity boots, like a bat, maybe it’ll all come back” - she scrapes up her skin, giving herself a finger face-lift - “I’d be hanging upside-down thinking, ‘it doesn’t look good that way either’. ”

Despite being 49 now, she was on Playboy’s final cover last year. “That was the last call I thought I’d get! Brandon was next to me and said, ‘You have to do it. It’s iconic, Mum.’”

Was it difficult for them having such a famous mother? “I’ve told them things age-appropriately. They’ve found out a lot in the school playground, and they’ve had fist fights over their mum, but now they get it. And I was hands-on. I never had nannies.”

She tried to encourage them to find careers outside showbiz but Brandon’s an actor and Dillon’s a musician. Brandon is also in a Dolce & Gabbana ad and once interned for Westwood. He ended up calling Anderson from the Arctic, where they were trying to stop drilling, saying, “what the heck’s going on? Vivienne’s yelling ‘where are the polar bears?’”

So is she a cool mum? “They think I do things wrong. It’s the typical mother-son relationship. ‘Oh Mum, you should have done this. You could be so rich like Kim Kardashian!’ That’s not a life I aspire to. I am rich: I’m healthy, I have two beautiful boys and I’m doing what I’m passionate about. I don’t need stuff.” She says that last word with disdain. And with that, she gives me a goodbye hug - and a reading list.

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