Kayleigh had bought a hand-made gold dress for the dance

Kayleigh Baker, 16, has also been thrown off the netball team at Hurworth School, near Darlington, County Durham, as punishment for the decision.

A school governor has quit in protest but the school insists the tough line on extra study benefits pupils.

It says teachers have the final decision on who attends the classes.

Kayleigh, who is a prefect at the school and already has two A grade GCSEs, said the row had placed her under a lot of stress.

"With the prom getting closer and closer I am getting quite upset because I won't be going.

"My friends have been great, as has my sister and parents, which has made it a little easier."

The row started last June when the school asked all year 11 parents to sign a form allowing their children to attend the sessions.

She has come home from school and just collapsed into my arms in tears

Mum Kay Baker

Kayleigh's parents, Kay and Ellis, did not sign, saying their daughter was already a high achiever who did not need the burden of extra classes.

Headteacher Dean Judson then wrote to them saying their daughter would be excluded from any "other voluntary activities" at the school.

This includes the end-of-school dance at Hardwick Hall, near Sedgefield, County Durham next month.

School standards

Mrs Baker, 38, said they had bought their daughter a long gold prom dress for the event.

She said: "There have been lots of times when she has come home from school and just collapsed into my arms in tears."

"I just cannot believe it has come to this."

School chief executive Eamonn Farrar said the extra study sessions were made compulsory five years ago.

He said: "If we were to give the children the choice of attending the extra study sessions, what do you think the response would be? They wouldn't attend.

"At the school we have standards and we extend these to the children. They have rights but they also have responsibilities too."