A tech developer with a successful London e-learning company has said he has already quit Britain after 10 high-flying years because of the uncertainty and “mindless tribalism” caused by Brexit.

Jan, an IT specialist from the former Yugoslavia, has set up a new business in Switzerland where he says the approach could not be more welcoming.

He said the drop in the value of the pound “killed” his business because the cost of paying subcontractors in places such as Romania and India has shot up, destroying his margin.

He also felt unwanted after the referendum and with a heavy heart he and his wife decided they didn’t “want to be trapped on an island that is descending into mindless tribalism” after 10 successful years here.

His story reflects the struggles of many small to medium-sized businesses hit by the collapse of the pound after the referendum and its continuing weakness today.

Jan, who did not want his real name used, managed to get well paid jobs in the capital and diverted some of his savings into a fund which eventually allowed him to set up his own business developing e-learning apps and games.

He won customers in the UK and a valuable client list in the US, and collaborated with tech giants such as Apple.

“Our products were winning awards regularly every year,” he said. “Then Brexit happened and the currency dive took its toll on our business. We were working with subcontractors all over the world and big fluctuations in currency and general instability is devastating to business.”

Jan, 42, has moved his business to Switzerland, where he works with clients including an aerospace firm.

He decided to move despite the fact he was generating “new money” for the exchequer through foreign clients. “With a heavy heart, we cancelled our mortgage plans, moved the family, opening up a company in Switzerland and slowly drained the UK company, moving all the private savings, and started to learn German. It was difficult and felt useless, but we didn’t want to be trapped on an island that is descending into mindless tribalism,” he said.

Born and raised in communist Yugoslavia, he says he remembers well what he describes as “Serbian nationalism, exceptionalism and tribalism” after the death of Josip Tito, the dictator.

He moved to London in 2005 and says he “got a very good job in a prestigious digital media studio”.

“I then started my own business with lots of American clients and paid a lot to Her Majesty in taxes. Life was great.”

He says Switzerland’s welcoming approach to business is in stark contrast to the UK’s since the referendum. About 25% of the population are foreign and all new immigrants are invited to a lounge party with the town’s mayor with free food and wine and a free city tour to help them get to know their new home.

“If immigration was the problem, Switzerland would be the poorest country on the planet,” he said. “Accountants tell me I am not the only one who has quit Britain and that they are swamped with small UK businesses setting up shop in Switzerland. The country is not in the EU but it couldn’t be more different than Britain post-2016.

“It is amazing to me that Britain by ‘wanting more control’ in 2016 decided to become more like Serbia in 1988 than Switzerland in 2018,” he said.

He said he is watching from the sidelines with interest but predicts mayhem in the event of a no-deal Brexit for small to medium-sized businesses with sub-contractors in Europe.

After Brexit he predicts it will become difficult to move money around, as he found out when he moved lock, stock and barrel to Switzerland.

“When I moved, the bank were imposing restrictions all of a sudden. It might have been to do with money-laundering measures, but the fact is it is difficult and who knows what will happen after Brexit? Who knows what the banks will do?” he said,.

“I would like to stress that we were pure net positive for UK, taking the money from US customers and bringing it to Her Majesty in the form of taxes. This was new money that did not exist before in the UK. Frankly, I still can’t believe what has happened and that a nation can work actively to chase out people like me.

“I still keep the company in the UK but only for minor UK-based transactions, and maybe in the tiny remote hope that this madness will be stopped.

“Nobody seems to care about how small businesses will function day to day with international trade and nobody is taking care of this in an organised manner. I decided I could not have my business held hostage so moved and I got out,” he said.

If you are a small business owner and are being impacted by Brexit, email lisa.ocarroll@theguardian.com