The 39-year-old had already invested €635,000 in Cocoon off Grafton Street and O’Reilly’s on Tara Street, which were owned by his friend, John Foley.
At the Employment Appeals Tribunal (EAT) retired accountant Charles Watchman said he told Irvine that he should not commit any further to the venture.
“I advised him to write off the funds already advanced,” he said.
However, Mr Irvine invested a further €635,000 and took a 50% stake in the holding company when the money was not paid back.
The tribunal heard that his business partner, Mr Foley, was dismissed for cashing personal cheques without the necessary funds and for paying off personal debts with company money.
Mr Foley is taking a case for unfair dismissal against Calview Investments, the owners of Cocoon.
Mr Watchman said his London-based accounting firm began working with Irvine’s on his British-based tax and investment affairs.
He said Mr Irvine’s decision to invest more money was a mistake often made by people inexperienced in finance or investment.
He added that another reason was his friendship with Mr Foley.
The case continues.