Sports Direct boss Mike Ashley once vomited into a fireplace after a senior management meeting held during a pub lock-in and would lie under tables and “take a nap” during meetings he found boring, a court has heard.

Ashley, the owner of Premier League Newcastle United FC, also “played a game of spoof” to decide who paid bank fees, it was claimed.

The claims emerged at the High Court where investment banker Jeffrey Blue alleges the businessman reneged on a commercial agreement worth £15 million – negotiated in a London pub in 2013.

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According to Mr Blue, the Sports Direct boss promised to pay him £15 million if he used his expertise to increase the company’s share price to £8 a share. He says Mr Ashley paid only £1 million.

Barrister Jeffrey Chapman QC, who is leading Blue’s legal team, told the judge Ashley’s business practices flew in the face of “business orthodoxy”.

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“Mr Blue refers to Mr Ashley lying underneath tables in meetings he found to be boring to ‘take a nap’, playing a game of spoof to resolve who ought to pay Merrill Lynch’s legal fees … (totalling £750,000) and lavishly entertaining Sports Direct’s non-executive directors,” Chapman outlined in written evidence to the court.

Mr Justice Leggatt began analysing evidence at a High Court hearing in London on Monday.

Chapman said the judge would have to consider the relevance of the fact that the discussion took place in a pub.

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He added: “Mr Ashley is not an ordinary businessman, does not conduct business in an orthodox way or in business-like environments.”

Mr Ashley’s lawyers have hit back at Mr Blue’s claim saying it is “remarkable” and an “opportunistic try on”.

The hearing continues.