When Theresa May meets Donald Trump for the first time as president this Friday, she has a lot to talk about. Most pressing, of course, is a post-Brexit trade deal between the UK and the US, the success of which will have a direct and lasting impact on the British economy. The Prime Minister will also raise the importance of Nato, after President Trump’s scathing and unsettling remarks about the defence alliance being “obsolete”.

May will be the first foreign leader to meet the new president. Both are in desperate need of political legitimacy for their own high-risk mission statements: in Trump’s case, for his protectionist new world order; in May’s, the uncertain future of drumming up trade for a UK outside of the European Union.

In this sense, it is a sign of both leaders’ weaknesses, not their strengths, that they need each other so soon. But nevertheless, when May addresses the economy, trade and defence in the White House, she does so as Trump’s equal (and, from all available evidence, as his intellectual superior). Trump, whose attitude to women is appalling, will not be used to a female politician talking tough on trade, finance, terrorism and defence.

May’s presence in the White House does not negate or undermine the millions of people who joined the Women’s March across the world at the weekend. It enhances it. To me, my feminism means equality with men – and that includes the power to tackle them on everything from treatment of women to the future of Nato. So if Trump can, as it were, trump May at their summit, it is only because he is an American president dealing with a British premier, not because he is a man dealing with a woman.

Theresa May confirms upcoming meeting with President Trump

I wanted Hillary Clinton to be president, and for this summit to be between two women, but we are where we are. So forgive me if I am cheered by the thought of a female politician – and a British one at that – on equal terms with the most powerful man in the world.

As May herself said on the Andrew Marr programme, her very presence sends a message to Trump about the role of women. What is more, she said she is “unafraid” to let him know that his language and attitudes toward women are “unacceptable”. She has said this in public three times now: first on Sky News earlier this month and again in an interview with the Financial Times on Saturday – this message will have percolated through to the White House.

Yet to some, May cannot speak truth to Trump because of her politics and her status. I have heard so often the fallacy that Conservative women cannot be feminists because they are Conservatives, as if Labour and other left-wing parties have exclusivity on feminism. This is self-defeating nonsense, and normally used as a cover for complaining that the Tories don’t care about social justice and the poor. I see it as legitimate to attack the Conservative government for its policies on welfare, but this shouldn’t be used to substantiate the lazy claim that they “hate women”.

After I endorsed May’s comment that her very presence in Trump’s White House sent a message to the president about the role of women, I was surprised to see JK Rowling, in response, tweet: “Yes, Trump’s about to meet an affluent white woman begging him for a trade deal. He'll be reading 'Feminism is For Everybody' by teatime” and: “Affluent white women have ‘been there’ all his life. How exactly will another one kowtowing to him reform him?”

In pictures: Women of the world march against Trump Show all 32 1 /32 In pictures: Women of the world march against Trump In pictures: Women of the world march against Trump London An image of President Donald Trump is seen on a placard during the Women's March in London, England Getty In pictures: Women of the world march against Trump Sydney A view of the skywriting word reading 'Trump' as thousands rally in support of equal rights in Sydney, New South Wales EPA In pictures: Women of the world march against Trump Rome People shout and hold signs during a rally against US newly sworn-in President Donald Trump in Rome Getty Images In pictures: Women of the world march against Trump London A protester holds a placard during the Women's March in London, England Getty Images In pictures: Women of the world march against Trump Marseille A placard ready 'Pussy grabs back' is attached to the handle bar of a bike during a 'Women's March' organized by Feminist and human rights groups in solidarity with women marching in Washington and around the world for their rights and against the reactionary politics of the newly sworn-in US President Donald Trump, at the Old Port (Vieux Port) of Marseille, southern France Getty Images In pictures: Women of the world march against Trump Bangkok A young Thai girl holds a "women's rights are human rights" sign at Roadhouse BBQ restaurant where many of the Bangkok Womens March participants gathered in Bangkok, Thailand Getty Images In pictures: Women of the world march against Trump Bangkok A Thai woman takes a photo of a "hate is not great" sign at the women's solidarity gathering in Bangkok, Thailand Getty Images In pictures: Women of the world march against Trump Bangkok American expats and travellers gather with the international community in Bangkok at the Roadhouse BBQ restaurant to stand in solidarity in Bangkok, Thailand Getty Images In pictures: Women of the world march against Trump London Protetesters gather outside The US Embassy in Grosvenor Square ahead of the Women's March in London, England Getty Images In pictures: Women of the world march against Trump Marseille Women's March at the Old Port (Vieux Port) of Marseille, southern France Getty Images In pictures: Women of the world march against Trump Marseille Protestors hold placards reading 'My body my choice, my vote my voice' during a 'Women's March' organized by Feminist and human rights groups in solidarity with women marching in Washington and around the world for their rights and against the reactionary politics of the newly sworn-in US President Donald Trump, at the Old Port (Vieux Port) of Marseille, southern France Getty Images In pictures: Women of the world march against Trump Rome A person holds a sign during a rally against US newly sworn-in President Donald Trump in Rome Getty Images In pictures: Women of the world march against Trump Kolkata Activist Sarah Annay Williamson holds a placard and shouts slogan during the Women's March rally in Kolkata, India AP In pictures: Women of the world march against Trump Kolkata Activists participate in the Women's March rally in Kolkata, India AP In pictures: Women of the world march against Trump London A Women's March placards are rested on a bench outside the US Embassy in Grosvenor Square ahead of the Women's March in London, England Getty Images In pictures: Women of the world march against Trump London A women carries her placard ahead of the Women's March in London, England Getty Images In pictures: Women of the world march against Trump Manila Women protesters shout slogans while displaying placards during a rally in solidarity against the inauguration of President Donald Trump, in suburban Quezon city, northeast of Manila, Philippines AP In pictures: Women of the world march against Trump Berlin Protesters attend a 'Berlin Women's March on Washington' demonstration in front of the Brandenburg Gate in Berlin, Germany AP In pictures: Women of the world march against Trump Berlin Protesters attend a 'Berlin Women's March on Washington' demonstration in front of the Brandenburg Gate in Berlin, Germany AP In pictures: Women of the world march against Trump Berlin Protesters attend a 'Berlin Women's March on Washington' demonstration in front of the Brandenburg Gate in Berlin, Germany AP In pictures: Women of the world march against Trump Melbourne Protesters take part in the Melbourne rally to protest against the Trump Inauguration in Melbourne, Australia Getty Images In pictures: Women of the world march against Trump Macau Protesters take part in the Women's March rally in Macau Getty Images In pictures: Women of the world march against Trump Melbourne Womens march on Melbourne protestors marching during a rally where rights groups marched in solidarity with Americans to speak out against misogyny, bigotry and hatred Rex In pictures: Women of the world march against Trump Macau Protesters hold placards as they take part at the Women's March rally in Macau Getty Images In pictures: Women of the world march against Trump Macau Protesters hold placards as they take part at the Women's March rally in Macau, Macau. The Women's March originated in Washington DC but soon spread to be a global march calling on all concerned citizens to stand up for equality, diversity and inclusion and for women's rights to be recognised around the world as human rights Getty Images In pictures: Women of the world march against Trump Manila A mother carries her son as they join a rally in solidarity against the inauguration of President-elect Donald Trump as the 45th President of the United States in suburban Quezon city northeast of Manila, Philippines AP In pictures: Women of the world march against Trump Sydney An infant is held up at a demonstration against new U.S. President Donald Trump in Sydney, Australia Getty Images In pictures: Women of the world march against Trump Sydney A woman attends a demonstration against new U.S. President Donald Trump in Sydney, Australia Getty Images In pictures: Women of the world march against Trump Sydney A woman expresses her Anti-Trump views in Sydney, Australia Getty Images In pictures: Women of the world march against Trump Sydeney Protesters demonstrate against new U.S. President Donald Trump in Sydney, Australia. The marches in Australia were organised to show solidarity with those marching on Washington DC and around the world in defense of women's rights and human rights Getty In pictures: Women of the world march against Trump London Protesters march from The US Embassy in Grosvenor Square towards Trafalgar Square during the Women's March in London, England Getty In pictures: Women of the world march against Trump London Protesters carrying banners take part in the Women's March on London, as they stand in Trafalgar Square, in central London Reuters

But no one is saying May is going to turn Trump into a feminist or “reform” him. What’s more, why does the fact that she is an “affluent white woman” delegitimise her presence or make anything she says about feminism carry less weight? I am not sure Rowling really believes that affluence precludes the right to speak up for women. Would she rather the Prime Minister were not there at all?

And there is another fallacy: that politicians from certain backgrounds should not speak for working class voters. Jeremy Corbyn’s supporters do not question his credentials on speaking for the working class, even though his background is as affluent as May’s.