LONDON (BLOOMBERG) - For Mr Julio Manuel Rios de la Rosa, Brexit changed everything.
The 28-year-old scientist arrived in Manchester five years ago and went on to work in a joint project of the university and AstraZeneca Plc. Although his contract had two more years to run, he quit and moved to Madrid in March, joining a small Spanish company testing cancer treatment.
"Before Brexit, I thought I would settle down in the UK because of its cutting-edge research, its global reach and the network," Mr Rios de la Rosa said. "But the idea of going through a tedious process of constant paperwork held me back."
Net immigration from the European Union to Britain fell to the lowest level in six years as the UK came closer to leaving the bloc and sterling dropped - even as Prime Minister Theresa May sought to reassure workers their status was safe even in a no-deal scenario.
Bank of England governor Mark Carney has warned that the UK is at risk of facing net emigration, hurting the economy, in a worst-case scenario of a disorderly departure from the EU.
Eight out of the 12 British nations and regions saw a net outflow of talent overseas in October, according to a LinkedIn report on Monday (Dec 10). The biggest exodus came from Yorkshire and the Humber, the North East, and Wales and London is still losing international talent, LinkedIn said.
Since 2015, interest in British jobs among Europeans seeking work has dimmed, according to hiring website Indeed Inc, which tracks clicks on postings. Ireland and Poland led the decline.
"Our findings will make worrying reading for employers in the UK's health-care and construction sectors," said Mr Pawel Adrjan, an economist at Indeed. "Both are already suffering skills shortages, and our research suggests this problem may worsen as more Europeans return to strong labor markets in their own countries or choose not to leave for the UK in the first place. "
It is not just foreigners walking off. British geneticist Emma Bell, 28, is preparing to move to Toronto to work as a cancer researcher. She has been thinking about leaving the UK since the Brexit referendum in 2016 - three of her colleagues have already relocated to Germany.
"We need basic chemicals in order to do research and I have absolutely no confidence that we're going to be able to get those in the year after March 29," she said, referring to Brexit day. "That's going to be detrimental to my career as well as cancer research in the UK for a good chunk of time."
To be sure, many are still drawn to Britain. Some 273,000 more people arrived in the year to June than left, the Office for National Statistics said last month. Non-EU citizens made up the bulk of those numbers but net migration from the bloc remained positive as well.
Seeking to end lingering uncertainty, Brexit Secretary Stephen Barclay has guaranteed the rights of EU citizens and their family members to "continue to work, study and access benefits and services on the same basis as now" in the event of a no-deal Brexit.
Yet Mrs May has said there will be no preference granted to EU nationals under Britain's post-Brexit immigration regime, which will be based on skills and the needs of employers.
Mr Rios de la Rosa has already made his decision.
"After the referendum, I was in shock, not only for the implications it had at a personal level - if we would need a visa or not, for instance - but also because the UK would be left out of research programmes," he said.