Tracy Worcester: 'Mummy's got to save the planet'

Life, for Tracy Worcester, is a series of battles. The one for which she is best known is her 23-year campaign to save the planet. Less well-known – and more recent – was a brief fight with breast cancer, which she seems to have won. And then there's the one against the monied elite, which she appears to be losing. Tracy is a reluctant marchioness, having married, in 1987, Harry Fitzroy Somerset, eldest son of the Duke of Beaufort. One day, her husband will become the 12th duke and inherit Badminton House in Gloucestershire, which comes with 52,000 acres, making it one of the biggest estates in the south of England. But no, it's not organic. They have three children, whom, she says, she has "lost" to boarding school, and her eldest is about to go into corporate finance – Tracy's enemy number one. But more of that later.

I've come to the family's bohemian Chelsea townhouse to talk about her latest work campaigning for pigs. Worcester, 54, divides her time between making films about appalling pig-rearing conditions and being a mother. Or, at least, working out how to: when her ten-year-old asked for help with his revision, she said, "Mummy's got a few things on – first, she's got to save the planet". Still, she has a sense of humour, as she tells that joke against herself. In 2008, she released a powerful and shocking film called Pig Business, which exposed the bully-boy tactics of the big corporations behind intensive pig farming. Now she has taken her campaign around the world, tailoring the film for other countries where intensive pig farming continues.

Tracy has just spent three months in Latvia, Chile and the Ukraine, filming additional material which she will now add to her film for release in each country. Just after she flew back from Chile, one of the locals she had been filming with, Yahir Rojas, who is campaigning against the giant pig farm built next to his home village of Freirina, was beaten up and thrown into prison. Tracy herself has been chased by farmers and threatened. Many foreign ministers won't now agree to be interviewed by her, such is her reputation for causing embarrassment.

She admits to "boring on", but she does more than just talk about her passions. I catch a glimpse of half a dozen people clattering away on laptops in the basement, all employees of her charity. We move upstairs to sit in collapsing sofas that compete for space with an exercise bike and three litres of vodka. Dressed in clashing knitwear, she is tall, slim and chaotically attractive. The first obvious question is, why travel the world tackling global problems, when her own farm isn't even organic?

"The bottom line is, we were asked to go out to these countries, because the film is being used as a tool to show that this is a global problem." Contrary to the assumptions about animal welfare campaigners overlooking the plight of humans, Tracy apparently also cares about people. "Where we were in Chile, there are 2.5 million pigs in the middle of a desert with a small river going through it. These water channels are shared with the local people. It's like, what the hell? The local people are angry and fighting it. There are just too many pig farms all in one place. The stench is unbelievable."

A shocking fact is that some of this pork can end up on British tables. That's because although, as Tracy says, Britain has the highest pig welfare standards of any country, we import a lot of meat. A recent report found that more than half the bacon sold in the UK comes from the Netherlands, Denmark, Germany and Italy, where farmers can keep sows in smaller pens and for longer periods. Some Chilean pork might be processed in the EU, and end up with a label that says "packaged in the EU". "Of all the pork that comes to Europe," says Tracy, "48 per cent of it is from Chile. There's some little loophole in negotiations with the World Trade Organisation that allows Chilean pork to come us."

Because Tracy is a marchioness, she is able to take this up with David Cameron at social occasions. She grew up in his Oxfordshire constituency, and never misses an opportunity to bend his ear at a party. She has a rather brilliant way of calling him "Cameron", as if talking about a pupil at school. "When I spoke to Cameron at something I met him at, I said: 'You're in my film, saying that, just like we don't import cars that have lower emission standards than we have in this country, nor should we import meat that has lower animal welfare standards than the ones we have in this country'. He said that we should have waited for the rest of Europe to have the same standards, before we jumped in ahead and lost our farmers as a result. And I said, 'I completely agree'. We exported the cruelty abroad. But that was before he got into power. The moment you get into power you're locked, it seems, into this global trade ideology."

For Tracy, the real problem is the global economy and the power of rich corporations over governments. As she puts it: "Whoever pays the piper calls the tune." She might see and like the Prime Minister socially ("he's very nice, actually"), but she's no fan of him politically. Like many greens, she's disappointed that he broke his promises to have the greenest government ever.

"I think he's totally been bought by the corporate right-wing agenda," she says. Once, she tackled him about our reliance on imported meat. "And he basically said, 'We need to help Africans by giving them our business'. So he went way off subject, nothing about the pigs. They don't come from flipping Africa!" Who would she vote for tomorrow? "For me, there is only the Green Party. I mean, I would probably vote for Ed Miliband, because I couldn't bear more Conservative [government]. I'm just hoping Miliband is a little more involved in people's welfare."

Saving the world is a never-ending battle, so what about that other one – the family's embarrassingly inorganic, but highly profitable farm? "The thing is, I have absolutely no control. My husband's father is running the farm and he doesn't believe that organic is the answer, though there are five big farms like his in the area, and his is the only farm that's not organic. I don't row because it's sort of obvious what I'd like. But I equally don't want the farm to go bankrupt."

Tracy started life as an actress and model – she played Miss Scarlett in a TV drama based on Cluedo, and starred in C.A.T.S. Eyes. Her sister is the actress Rachel Ward. But in 1987 she married Harry Worcester, then one of society's most eligible bachelors, and gave it all up to have children. Some would see that as a sacrifice, but for Tracy it meant a new freedom. "I was allowed to get out of earning a living, being an actress and having to make money to pay my mortgage. I stopped all of that, and had a family, and felt free, to think and do what I want."

Does she miss her old life? "To be honest, I much more enjoy working with people and for people. Acting, for me, was very 'ego'. Am I any good, how big is the audience, do they want to buy a ticket for me? It was all about me." She made a decision to dedicate herself to campaigning "after my marriage". "Bunter" Worcester, as he's known to friends, is a familiar face at fashionable society parties, though you rarely see Tracy with him. What does her husband make of her work? "He's not interested. I do my own thing." That sounds like a healthy relationship, I say. She raises an eyebrow and laughs a long low rumble.

Marrying old money has enabled her to fund her passions, but it hasn't been without its price. Tracy is particularly angry that she had to send her three children to boarding school. "I thoroughly disapprove of boarding school, 100 per cent. I want to be a mother. I want the children who've I've bought into this planet to meet my friends, talk to me; I don't want them to be in a dormitory with a whole lot of girls, giggling and writing stupid things on the internet and putting crosses on each other's doors, and dressing up... I think that silliness rules. I just feel I've lost my children. And I don't want that. I don't respect these institutions. I don't respect that 5 per cent go to private school." Did you have to send them? "No, but I'm married."

Tracy is not the sort to stop fighting, but it can get exhausting. She boycotts all major chains, such as Starbucks, and used to sit in the car when her children went into Tesco, though now she joins them. "I'd rather be in there saying, No! No! No! Oh, my god, here, this section please, the organic section!"

Perhaps the biggest kick in the teeth is that her eldest son, Robert, Earl of Glamorgan, has just graduated in engineering and finance, and is about to take up a job in the City. "My attitude to that is, if you don't understand the system, you can't really criticise it." Does she mind? "What can you do? Absolutely nothing. But he's going to go in and learn all about it and change the system from the inside. He'll be a turncoat!" Somehow, it seems unlikely, but with Tracy around, there's always hope.

Curriculum vitae

1958 Born Tracy Ward, daughter of the Hon Peter Ward and Clare Baring. She was later the lover of Lord Lambton, and lived with him at Cetinale in Italy. Tracy grew up at Cornwell Manor, Oxfordshire. She went to boarding school from an early age, but was expelled several times, once for allegedly hitting the deputy headmistress.

1980 After working as a model in Paris, then at Christie's in New York, becomes an actress. Roles include Pru in the TV detective series C.A.T.S. Eyes.

1987 Marries Henry Somerset, Marquis of Worcester, eldest son of the 11th Duke of Beaufort. Moves to the Badminton estate, and insists on not flushing the loo to save water.

1989 Starts working for Friends of the Earth, later becomes a patron of the Gaia Foundation and joins the board of The Ecologist. Has first son, Robert, Earl of Glamorgan.

1990 Plays Miss Scarlett in the TV drama/gameshow hybrid Cluedo.

1991 Has a daughter, Lady Isabella Somerset.

1995 Has a second son, Lord Alexander Somerset.

2008 Releases her animal welfare film Pig Business.

2012 Shoots new footage from around the world to include in versions of Pig Business for export to Chile, Ukraine and Latvia.