SimplyBiz founder Ken Davy is among the more than 300 business men and women to sign a letter calling for Britain to leave the European Union.
The chairman of SimplyBiz has joined Peter Hargreaves, the founder of Hargreaves Lansdown, to advocate a so-called Brexit.
Mr Davy told Financial Adviser: “As far as I am concerned, the EU is trapped in the slow lane of history and the UK will be much more successful and have complete control of its own destiny if we leave.
“I am very keen to support the Leave campaign and do everything I can to generate success for it.
“Leave aside all the arguments about not controlling our own borders, we are being handicapped as a country.”
In March, Mr Hargreaves signed 15m letters which were sent to households around the UK as part of the Leave campaign.
At the time he accepted there would be “short-term volatility” in the event of a decision to leave the EU, but said the decision facing voters at the referendum on 23 June was a long-term one.
In March half of the advisers polled by technology firm Intelliflo would welcome Britain leaving the EU, with one in five saying a Brexit would have no impact on their clients’ wealth.
Harry Katz, who ran adviser business Norwest Consultants for 25 years until last year and is now a consultant, said he favours staying in the EU.
He said: “Forecasts about what may happen are ridiculous. I cannot tell Ken how good it is going to be if we stay in and he cannot tell me how good it will be if we leave.
“Germany is in the EU and they don’t have a problem with trade. We have got a problem with trade because we are plonkers, not because we are in the EU. Isn’t it sad that Germany sells more to the Commonwealth than we do?
“Being in a large group is better than being in a small one - even the Romans knew that.”