A private school is facing a revolt by 250 parents after a popular head teacher was asked to leave.
Parents have protested outside the school
Bury Lawn School in Milton Keynes, Bucks, has had five heads since it was bought by Global Education Management Systems (Gems) two years ago.
Parents are angry that the previous acting head was asked to go last week, just before A-levels, and say they might remove their children.
But Gems said staff changes had been in the "best interests" of Bury Lawn.
The Dubai-based company, which runs 13 schools in the UK and 200 worldwide, charges annual fees of between £5,000 and about £8,000.
It advertises its education as a more affordable alternative to normal private schools, still offering high academic standards.
But members of a 250-strong parents' campaign group are angry that acting head and history teacher Mark Olejnik was asked to leave.
Tearful students reportedly walked out of lessons in protest.
Mr Olejnik, who had taught at Bury Lawn for 18 years, had been due to leave for another job at the end of the summer term.
A family spokeswoman said: "The parents have been fantastic with their support. Everyone's ringing up.
"Mark wanted to complete the year's tuition for the pupils' sake."
Sheena Wilson, whose three sons attend the school, said: "There were children in floods of tears, staff in tears and parents were very, very upset."
The parents are demanding to know why Mr Olejnik had to leave early.
Phil Martin, who has three daughters at Bury Lawn, which takes children from nursery to the age of 18, said Gems had demonstrated a "lack of communication".
He added: "We are left feeling empty and betrayed. It is uncomfortable and distressing that parents are forced to act in this manner to get their voices heard."
Gems said in a statement: "The group will always reserve the right to make teaching and management changes that are in the best interests of the school.
"This it did in relation to asking Mr Olejnik to leave early and for other changes that have taken place in the course of the last year.
"Throughout this period the school has never been without the significant support of the global organisation in terms of additional senior teaching and other support staff as well as access to substantial resources."
The company said it had "greatly improved" the curriculum at Bury Lawn and was building a performing arts suite, music rooms and a £2m sports hall.
It continued: "Bury Lawn is already a good school, it will very shortly become a great school."
An Independent Schools Council spokeswoman said inspectors would visit Bury Lawn "as soon as it can be arranged" and decide whether any action was necessary.