The Institute has sent out a grovelling letter of apology to such arts luminaries as Rachel Whiteread and the film-maker Jane Campion, whose names appear underneath the masthead on the ICA's official stationery.
Last month Ivan Massow, the recently appointed chairman, warned that celebrities who had, in his opinion, made little effort to be involved in ICA, "may stop being patrons".
In a leaked memo Mr Massow added that replacements would be selected on the basis of their contribution to the contemporary art world.
But Philip Dodd, director of the ICA, has written a letter of apology in what insiders say is a hasty attempt to "calm the waters" and prevent further public criticism of the ICA from offended patrons. It is understood Mr Dodd is concerned it could be difficult to recruit new patrons.
It is also understood that Mr Massow's comments were directed at Joanna Lumley and Madonna, who have lent their support in name only to the ICA.
Recent criticism that the ICA is not "fresh and contemporary" is understood to have been the catalyst for Mr Massow's original comments.
For example, the recent exhibition by Dutch architect Rem Koolhaas in July was considered by some insiders to not have been obscure enough.
The personal artistic taste of Mr Massow, who made his fortune from selling financial services targeted at the gay community, extends to a handful of Russian portraits from the early 20th century.
It also includes a print by Leon Kossoff of Christ Church, Spitalfields, as well as a Horst portrait of Bette Davis which is in Mr Massow's bathroom. His collection also includes works by Sacha Newley, who is Joan Collins's son and a friend of Mr Massow.
The ICA chairman has admitted that he feels more comfortable in his wellies than partying in London. "The countryside is where I feel at home. I'll go to a glam party as long as it's Monday to Wednesday, but the rest of the time I'll be in my cottage cooking a roast."
Yesterday Mr Dodd said that the chairman's comments were just "personal opinion" and that the Institute appreciated that many of its members were very hardworking.
He refused to comment on plans to drop Joanna Lumley or Madonna although he confirmed he had contacted sponsors after Mr Massow's comments.
"I have written a letter apologising to people and explaining that it's the silly season.The position is that we have made no decision. Some of these people have worked extremely hard in lots of ways for the ICA, such as Rachel Whiteread and Jarvis Cocker.
"If any changes are going to be made the patrons themselves will be the first to know. We have no direct control over who is chosen. That is a board decision."
A spokeswoman for Joanna Lumley said her agent was too busy to ask the actress for a comment, and "we can't make comments on Joanna's behalf".Reuse content