Thornton Grammar School has issued a warning about the length of skirts – even banning one type because it can ride up so high it looks as if students are actually not wearing one.

Deputy headteacher Liz Dawson has given parents until after the Easter holidays to comply with the request banning the tubular skirts which she says are inappropriate as school uniform.

In her letter, the deputy head of the school in Leaventhorpe Lane said: “I wrote to parents last year concerning the fashion for tubular skirts which resulted in some girls wearing these for school.

“Our concern is that during the day these skirts regularly ride up to the length of the blazer, giving the appearance that no skirt is being worn.

“Whatever the length of these tubular skirts, because they ride with wear, all skirts of this design are inappropriate as school uniform. The published school uniform states that skirts should be plain black in a style suitable for school about knee length.

“We ask that a skirt which meets the published school uniform criteria is worn as soon as possible or that your daughter comes to school in appropriate black trousers.”

It comes just months after Guiseley MP Stuart Andrew gave his backing to Guiseley School after it announced a ban on skirts from January amid fears that girls were putting themselves into “undignified” situations by ignoring rules on skirt length.

Mr Andrew said at the time that the sexualisation of children was an increasing issue.

“If the school is finding that this is a problem then I back staff in trying to resolve it,” he said.

“I admire them for confronting this issue and the pressure on some young girls must be enormous.”

Immanuel College, Thackley, has also banned skirts from its school uniform because of rising hemlines.

That happened last summer and Bingley Grammar banned its pupils from wearing skirts in September 2009.

Mrs Dawson said that the letter was initially sent out a year ago and the latest letter was a reminder.

“These skirts are elasticated no matter what the length they ride up, so we took the decision to inform parents they were inappropriate,” she added.

“They were constantly being pulled down and this is just a reminder giving people the opportunity with three weeks notice over Easter to make sure they adhere to the published regulations.”.