US firm Sonnenschein Nath & Rosenthal gave its London practice a unanimous vote of confidence just seven months before axing it.
Sonnenscheins is to close its eight-strong London office on 1 December (The Lawyer, 27 September).
Sources say the closure of the office came as "a complete shock" to its lawyers because a full partners meeting in Chicago voted unanimously in February to back a business plan presented by the London office.
It is understood the plan was called for after US partners became impatient at the length of time it was taking to make a profit in London.
But having backed the plan for London, Sonnenscheins' US management then began merger talks with UK firm Warner Cranston.
It is understood these were carried out with little or no consultation with the partners at the London office.
Warner Cranston told The Lawyer last week it had broken off talks with Sonnenscheins last month. Contrary to recent reports, discussions had ended before the announcement of the London office's closure.
The Lawyer understands Sonnenscheins' announcement to partners on 20 September came within 24 hours of Warner Cranston's rebuff, and that this was the trigger to shut down the London operation.
The office's eight lawyers were shocked at the news because they believed the vote of confidence had secured their future. Former Allen & Overy partners Rupert Jones and Peter Borrowdale and their fellow partners Antoinette Tucker and Jonathan Griffiths are left with the prospect of being jobless just before Christmas.
Sonnenscheins' chairman Duane Quaini would not confirm the vote at the partners meeting in Chicago.
"I cannot comment on internal firm decisions for obvious reasons," he says.
Partners at the London office are remaining silent under orders from Chicago as they negotiate their leaving payments.
Quaini says he is "putting together as generous a package as possible.
"That is our biggest and most significant concern because we have a group of absolutely terrific people extending down from Peter Borrowdale to our associates and staff".