Mr Blue said he had attended several senior management meetings at another pub, the Green Dragon in Alfreton, Derbyshire.
He said: "These meetings were like no other senior management meeting I had ever attended in all my years of investment banking experience."
Finance expert Jeffrey Blue said Mr Ashley "was like no other client"
Describing it as a "pub lock-in" where fish and chips and kebabs would be brought in after closing time, he said: "On one such evening, in front of his senior management team, Mr Ashley challenged a young Polish analyst in my team, Pawel Pawlowski, to a drinking competition.
"Mr Ashley and Pawel would drink pints of lager, with vodka 'chasers' between each pint, and the first to leave the bar area for whatever reason was declared the loser.
"After approximately 12 pints and chasers Pawel apologised profusely and had to excuse himself.
"Mr Ashley then vomited into the fireplace located in the centre of the bar, to huge applause from his senior management team."
Mr Blue said he first met Mr Ashley while working for Merrill Lynch in 2006.
"Mr Ashley was like no other client that anyone at Merrill Lynch had ever come across," he said.
"By way of example, his ability to express boredom and frustration during client meetings knew no limits, including various episodes where he would lie underneath meeting room tables to 'have a nap'."