(Bloomberg) -- PricewaterhouseCoopers LLP is facing allegations of a “shocking breach” of confidentiality by one of its former partners over a “quiet coffee” with a banker. 

The ex-partner held an “illicit meeting” with a banker advising law firm Slater & Gordon Ltd. spilling details of strategy and financial conditions of the then distressed Quindell Plc, now called Watchstone Group Plc., their lawyers said in UK court filings. 

The “outrageous nature of PwC’s conduct” in the breach, its non-disclosure, and the continued defense “makes it a paradigm case for the court to correct any more general misapprehensions in the market that this sort of conduct is acceptable,” Watchstone’s lawyers said in written arguments ahead of the London trial. 

Watchstone is seeking £63 million ($77.6 million) in its London suit. Lawyers said Slater & Gordon would have agreed to pay at least £700 million, instead of £637 million, in the 2015 deal for Quindell’s legal services arm had it not taken advantage of the information. 

“We deny these allegations and are vigorously defending this claim,” a PWC’s spokesperson said. The auditor’s lawyers argued in court documents that it’s “a surprising claim.” Quindell’s unit was worth substantially less and the deal was disastrous for Slater & Gordon, which had to write down the investment a year later, they said.

Watchstone declined to comment.

“Slater & Gordon has no financial interest in these proceedings,” spokesperson for the law firm said denying allegations of any wrongdoing.

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