BORIS Johnson has set out his post-Brexit trade pitch to African leaders with his vision to put "people before passports" in an immigration system overhaul.

The Prime Minister was tempting premiers from across the continent with the UK's financial and education systems as he opened his investment summit in London's Docklands this morning.

He also announced an end to UK support for thermal coal mining or coal power plants overseas in a bid to use trade to tackle the climate crisis.

In a separate development, Mr Johnson also met the Duke of Sussex in private with no aides present for about 20 minutes at the margins of the summit.

The behind-closed-doors discussion came the morning after Prince Harry said there was "no other option" but for him and his wife Meghan to stand down from the Royal Family.

With the EU departure coming on January 31, the PM was pledging to be a partner "through thick and thin" with African nations as he eyes fresh trade deals across the globe.

It is estimated that between now and 2050 Africa is set to see a 54 per cent of all the world’s population increase with 1.1 billion middle class Africans by 2060.

Mr Johnson made a pitch for improved business links from his proposed Australian-style immigration system.

"Change is coming and our system is becoming fairer and more equal between all our global friends and partners, treating people the same, wherever they come from," he told the UK-Africa Investment Summit.

"By putting people before passports, we will be able to attract the best talent from around the world, wherever they may be."

The PM gave current partnership examples of Nigerian street lights being stocked with low-emission diodes from Dorset and Angolan families tucking into chicken from Northern Ireland.

"We want to build a new future as a global free-trading nation, that's what we will be embarking on on January 31," he declared.

"But I want to intensify and expand that trade in ways that go far beyond what we sell you or you sell us. I've just told President Museveni of Uganda that his beef cattle will have an honoured place on the tables of post-Brexit Britain."

But - in an unwelcome eve-of-summit development for organisers - leaked documents exposed by media outlets including the BBC and the Guardian alleged that Africa's richest woman amassed her fortune by corruption and exploiting her nation.

Isabel dos Santos was forced to deny allegations that she got access to lucrative deals involving land, diamonds, oil and telecoms when her father was president of Angola.

Mr Johnson also spoke of the climate crisis and fight to save biodiversity by ending direct official development assistance, investment and export credit as part of his coal plan.

"There's no point in the UK reducing the amount of coal we burn if we then trundle over to Africa and line our pockets by encouraging African states to use more of it.

"To put it simply, not another penny of UK taxpayers' money will be directly invested in digging up coal or burning it for electricity," he insisted.

The PM was meeting presidents from Rwanda, Ghana and Nigeria at the summit and was due to have talks with the premiers of Egypt and Kenya at Downing Street tomorrow.

At Buckingham Palace this evening, the Duke and Duchess of Cambridge are set to host a reception to mark the summit.

Meanwhile, a report by Oxfam found the 22 richest men in the world have more wealth than 325 million women in Africa.

The Time to Care report said the gap between the rich and poor had worsened by the global economy's failure to reward women who provided care for children and the elderly for little or no pay.

The report was also published ahead of the World Economic Forum on Wednesday when some of the world's most wealthy and influential people descend on Davos in Switzerland.

Oxfam said the findings illustrated how "inequality continues to be at crisis levels with wealth valued over work and the contribution of women under-rewarded".

The world's 2,153 billionaires had more wealth than 4.6bn people in 2019, researchers found, while the world's 22 richest men owned more wealth than 325m women in Africa.

Oxfam compared the Forbes' 2019 Billionaires List to the total wealth of all African women aged 20 and over, including all women, not just the poorest 50 per cent.

The charity said women and girls were putting in 12.5bn hours of unpaid care work every day such as looking after children and the elderly, which contributes 10.8 trillion dollars a year to the global economy.

This was more than three times the size of the global tech industry, Oxfam said.

Some 42 per cent of women of working age cannot get jobs because of unpaid care responsibilities, compared to just six per cent of men.

Danny Sriskandarajah, Oxfam GB Chief Executive, said the findings of the report showed the "economy is just plain sexist".

The charity is urging governments to crack down on tax loopholes and get the richest one per cent to pay extra taxes.

It is also calling for investments in water and sanitation, electricity, childcare and public healthcare, which they say could save African women significant time.

Oxfam found that improved water sources in parts of Zimbabwe could save women up to four hours of work a day.

"When 22 men have more wealth than all the women in Africa combined, it's clear that our economy is just plain sexist," claimed Mr Sriskandarajah.

"One way that our upside-down economic system deepens inequality is by chronically undervaluing care work, usually done by women, who are often left little time to get an education, earn a decent living or have a say in how our societies are run, and are therefore trapped in poverty.

“If world leaders meeting this week are serious about reducing poverty and inequality, they urgently need to invest in care and other public services that make life easier for those with care responsibilities, and tackle discrimination holding back women and girls," he added.