Media playback is unsupported on your device Media caption US political climate is having an effect on new talent, says John Collison

Anti-immigration rhetoric coming from the White House is deterring software developers from going to the US.

That's according to the world's youngest self-made billionaire, 27-year-old Irishman John Collison.

Stripe, the company he founded with his brother Patrick, provides the payments plumbing for hundreds of thousands of online businesses.

Collison said that his fast-growing business had noticed the difficulty in luring top talent to Silicon Valley.

In an exclusive interview with the BBC, the Limerick man said he feared the same may prove true for the UK because of Brexit.

"People are less willing to move to the US," Collison said. "They don't even want to enter the visa process because of the perceived political climate here and how welcoming it is to immigrants and I think the perception (of the UK) will also make it harder to recruit in the UK"

He said the stakes were high as it ultimately risked the UK's ability to produce a vibrant and successful technology sector.

'The brightest and the best'

Collison has accepted there is no going back but says the government should be a sending a clear message that international talent was welcome in the UK.

"What's done is done but what I think we can now affect is the perception of the UK as an attractive place to live, work and do business, " he said.

"It's something we are screwing up in the US and I think there is a very clear opportunity to send a message that the UK is a good place to emigrate to."

Collison's frustration is compounded by the fact that these perceived forces of deterrence fly in the opposite direction to the way the world of commerce and technology are evolving.

He says: "There is a juxtaposition between an outward, global, technology and export-based economy on the one hand and the anti-immigrant signals from the US and Brexit."

The UK government insists that it understands the need to lure the "brightest and best" from around the world - it recently doubled the number of visas available for exceptionally talented individuals from outside the EU who show promise in technology, science, art and creative industries from 1,000 to 2,000.

But the long-term position of EU nationals who arrive after Brexit is less clear.

Image copyright Getty Images Image caption Stripe has just signed a deal with Amazon

That is perhaps one reason why Collison and his older brother are betting big on Dublin as their European headquarters.

"There are a few reasons. First, it's in the European Union, second, it's a real international melting pot with the skills we need and third it's a nice vibrant city to live in - there's more of a craic (more fun) in Dublin."

The $9 billion men

Stripe currently employs over 700 people in California, over 100 and rising in Dublin with just 25 in London.

Its backers include technology royalty like Tesla founder Elon Musk, Peter Thiel (one of the first investors in Facebook) and head of internet king-maker Sequoia Capital, Mike Moritz.

Stripe recently signed a deal with Amazon about which Collison remains tight lipped but is thought to have justified - or at least contributed to - its mind boggling valuation of over $9 billion.

"They are a customer but I'm not allowed to talk about it," he says.

Despite detecting some off-putting mood music from the US and the UK, its hard to dent the mood of a 27 year old whose second business - he and his brother sold one when they went to university - has such a huge market value.

Although Collison has plenty to crow about, he comes across as a very modest, thoughtful entrepreneur.

All the more reason to hear his experience of how young technology talent is seeing the world.