If you were prepared to protest against Donald Trump, why aren't you protesting against Mohammed bin Salman?

Britain is well and truly rolling out the red carpet for Prince Mohammed bin Salman of Saudi Arabia this week. The so-called reformer and de facto leader of his country won’t just meet our Prime Minister and other top officials tomorrow. He’ll be treated to dinner with the royals at Windsor as he looks to strike up deals diplomats say could be worth more than $100bn (£72bn). Someone’s even put mysterious “welcome” advertisements for the Prince alongside the M4 for the drive into London from Heathrow.

The reasons for the visit are clear. Saudi Arabia is trying to both project a new image of moderation to the world, and also build upon the deep trade and business ties that already exist with the UK. The planned initial public offering of state energy giant Saudi Aramco is expected to come up in discussions, with the London Stock Exchange competing with New York and Hong Kong for a potential overseas listing by the company.

Britain’s relationship with Saudi Arabia has increased in importance since the Government decided to end free trade with our closest neighbours. Now they’re desperate to deepen ties with non-EU countries willing to buy our goods and services. The UK already sells the Saudis billions of pounds worth of military hardware – and the Government wants them to up their orders.

Behind the smiles and handshakes on show tomorrow, and despite Prince Mohammed bin Salman’s attempts to be a poster boy for progress, there are some uncomfortable truths about his repressive government that must not be forgotten.

Life inside Saudi Arabia is brutal, with floggings and executions commonplace and elected government a distant dream. The country exports suffering, too. Their military intervention in Yemen’s civil war has led to thousands of civilian deaths and famine. According to Amnesty International, the Saudi attacks appear to have “deliberately targeted civilians and civilian objects such as hospitals, schools, markets and mosques”. Mohammed bin Salman hasn’t been a bystander in these attacks – he has overseen the three-year bombing campaign since day one.

And it’s not just Yemenis who have suffered at the hands of Saudi Arabian brutality. There’s also evidence to suggest Saudi Arabia has backed extremist Islamist groups wreaking terror across the world. The Saudis’ links with Isis, for example, are made plain in emails leaked from the office of Hillary Clinton, US Secretary of State from 2009 to 2013. They might be considered a close ally by Downing Street, but they’re also accused of aiding and abetting those who seek to harm us.

The record of the Saudi regime – and Prince Mohammed bin Salman’s role – make it clear to me that he should never have been offered the trappings of this visit. I was one of those who stood against a state visit for Donald Trump, but the case against this Saudi royal trip is even stronger.

No one is saying we should cut diplomatic ties entirely, or assume that Saudi Arabia will never change. It is the height of folly to refuse to speak with those whom you disagree with – and the positive, if very small, steps forward in Saudi domestic policy are indeed welcome. We’re simply demanding the terms of our relationship, and the lavishness of our welcome, are not set by the military industrial complex, or the British Government’s desperate desire to strike trade deals as we head towards Brexit.

Instead of falling over ourselves to appease Saudi Arabia, we should reset our relationship on equal footing, by ending all arms sales to the regime. Such a move isn’t easy because the arms industry exists at the nexus between our country’s industrial and foreign policies. Changing course isn’t just a foreign policy decision; it affects our industrial strategy too. That’s why we must accompany the end of arms exports to repressive regimes with a 21st-century industrial policy, which turns jobs in the industry into employment for the future.

Tory MPs are increasingly desperate to sling mud at political opponents for their relationships with foreign regimes, but it’s about time they got their own house in order. We should be in no doubt that the arms sales that may be agreed this week could feed wars and repression in the future – and as such we should be banning those sales for our own security as much as anything else.

Tomorrow, people will gather outside Downing Street demanding this Government ends its cosy embrace of the head-choppers of Riyadh. The message is clear: British diplomacy shouldn’t compromise on human rights, nor should it bend to the will of arms manufacturers.

At this most crucial time, Britain should send a signal to the world: we won’t roll out the red carpet for dangerous men who refuse to comply with at least the minimum standards of decency towards their fellow human beings.

Caroline Lucas is the co-leader of the Green Party