The chairman of English National Opera Martin Smith has stepped down following threats of industrial action and public criticism of his leadership.
Mr Smith was elected ENO chairman in 2001
The announcement follows the release last week of an open letter, signed by the author Jeanette Winterson among others, calling for his resignation.
"It is clear my ability to continue helping ENO has been damaged by a campaign against me," said Mr Smith.
His deputy Vernon Ellis becomes acting chairman while a replacement is sought.
Mr Smith's departure follows that of chief executive and artistic director Sean Doran in November.
Earlier this month ENO staff voted unanimously to ballot for strike action over pay and pension demands.
That vote was followed by the publication of the open letter which claimed Mr Smith's chairmanship had "brought about a crisis point".
The signatories - who included former ENO head David Pountney, broadcaster Libby Purves and composer Jonathan Dove - were critical of the board's decision to appoint a new chief executive and artistic director without advertising the posts.
In a letter to the ENO board, the outgoing chairman said it would "no longer serve the best interests of ENO to continue in office".
ENO staff recently voted to ballot for strike action
He also accused the media of "persistent hostility towards the board, and in particular to me".
"The company is in the best shape it has been in for many years," he wrote.
"Yet the media together with certain members of the arts community... are campaigning with relentless vigour to force me to step down.
"This has provided a continuously unpleasant and unhelpful background to our efforts to rebuild ENO."
On behalf of the ENO, Mr Ellis said the board was "deeply grateful to Martin Smith for his dedicated contribution during the past four-and-a-half years.
"His achievements should not be ignored."
Charity group Arts and Business, which encourages partnership between the two fields, has reacted with dismay to Mr Smith's resignation.
"This is a challenging day for those of us who wish to see individuals balance a distinguished career in business with an enormous personal and professional commitment to the arts," said chief executive Colin Tweedy.