A new Brexit could "seriously harm foreign investment in the UK," says a new study

Dharmash Mistry, chairman and co-founder of venture capital firm Lakestar, said if the UK does not strengthen a positive environment, it would lose foreign investors to other European markets.

"When there is uncertainty, many investors are waiting to see how the future will evolve before using too much capital," he told CNBC via email. "Talent will wait to see if they can live on in the UK before they move, and today it will and will be more and more of a concern if we do not stop the tide."

He said companies needed cross-border mobility of talent, more government capital and a regulatory framework to stay attractive to overseas investors.

However, Zoe Chambers, chief executive officer of Octopus Ventures, said that despite political uncertainties, business is still going on and innovative industries such as artificial intelligence have prevailed.

"There is a lot of capital in the market," she told CNBC over the phone. "More and more US investors are looking to the UK and Europe – historically they have only invested in domestic companies, but they are increasingly willing to invest across the pond."