Mr Hummler, who is also chairman of the Swiss daily newspaper Neuer Zuercher Zeitung, has previously been unusually outspoken among Swiss bankers in calling for the country's authorities to block any disclosure of banking client details to the US authorities.
Anchin, Block and Anchin described Cornwell as a demanding client who would use the firm for everything from arranging care for her mother to taking her clothes to the tailor.
And, Block trained the tax preparer in this manner because it knew that if the client learned that the Rapid Refund was not a refund but a high interest loan, many would decline the program.