The charity comprises no more than 12 volunteers who work in the Mexicali area of Mexico providing clothes, transport, food and legal aid to the thousands of migrants.

Founder Kelly Overton, who is in his 50s, said he had started the organisation after learning about the migrant caravans and realising there were few resources for those trapped there while their lives were in limbo.

He had no idea that royal couple even knew of the charity’s existence before he awoke yesterday morning to a sudden barrage of interest.

“The world reacts to celebrity,” he told the Telegraph. “And these two are among the most famous people you can get in the world.

“This kind of gesture draws attention to us, it leads to online follows and donations. And looking at the bigger picture, this situation needs to change so the more people around the world who hear about these unlawful policies the better.”

Mr Overton, who has masters degrees from both Harvard and Columbia universities, said the migrant crisis at the Mexico border was “one of the most inhumane and unfair” crises ever seen, likening.

“I’m ashamed of this country I’m from,” he said. “To treat people like this is just beyond belief and we see on the ground that it’s getting worse.

“Our response is in direct response to President Trump’s immigration policies. We work with women and children who are incredibly vulnerable, who have nothing when they arrive at this city in the desert.”

He has noted that if “white kids were taken from their parents and put somewhere” there would be international outrage.

The Sussexes had asked their one million plus followers to make suggestions about their favourite organisations and said the ones they had chosen  “represent the shared value of togetherness” the couple experienced during their recent tour in southern Africa.

One of those highlighted is the Bristol-based One25 Charity that helps women sex workers.

It is where the Duchess famously wrote inspirational messages on bananas to be handed out to the women when she visited in February.

The Essex-based Lotus Petal family support group said it was “incredibly grateful” that its “little page” been chosen by the royals, adding that it was “wonderful to be able to highlight maternal mental illness among many other deserving causes.”

Another of the charities, 52 Lives, aims to change one person’s life every week of the year and has previously won praise from David Cameron.