The board changes, to be debated by the Zoological Society of London's ruling council, are the result of faction-fighting caused by the board's abortive attempt to dismiss Jo Gipps, the zoo's director, last month.
But Mr Gipps has kept his post and now it seems a large proportion of the eight- strong advisory board is on the verge of losing theirs. Both supporters and opponents of Dr Gipps say they regret the deep divisions.
A majority of the board had lost confidence in Mr Gipps' ability to run the zoo. The board exists to advise the council of the Zoological Society, which owns the 167- year-old institution in Regent's Park. It voted to sack him with immediate effect last month.
But the 22-strong council, which met a few days later, criticised the board for acting beyond its powers. And while several members expressed doubts about Dr Gipps's competence, it rejected the dismissal and set up a three-man review group to consider the board's future and its relations with the council and the director.
The review's recommendations will be presented to tomorrow's council meeting. The Independent understands that it wants John Edwards, a London solicitor, and Martin Rowson, a cartoonist whose work features in the Independent on Sunday, to quit. Both were opponents of Dr Gipps.
Colin Tudge, a writer and conservation expert who also opposed the director, has resigned from the board. The board chairman, Peter Wrangham, an international banker, has also quit that post, although he remains treasurer of the society.
Dr Michael Brambell, a member of the review group and director of Chester Zoo, is tipped to chair the new board.