Students’ coursework has been lost after a technical glitch in the IT network at Saffron Walden County High School.

Headteacher John Hartley has assured parents it will not affect the grades of any student.

But it has left some pupils “distraught”, said Leigh Cromwell, whose daughter is in the sixth form.

Mr Cromwell said: “I think it’s frightening that a school of the reputation and stature of Saffron Walden County High can let such a catalogue of errors happen.

“I’m sure many pupils are distraught having put in all that effort on work that has subsequently been lost.”

He added: “The resilience of the school network, their back-up procedures and disaster recovery plan all appear to need a thorough review and, following that, stringent ­testing must take place to ensure that this kind of incident does not happen again.

“My main concern is that this string of ICT issues does not impact my daughter’s results and I’m sure many other parents and pupils have the same concerns and need the same reassurance.”

Mr Hartley said an investigation had been launched to find out what caused the failure, which he described as “highly unusual”. The school is reviewing its disaster recovery procedures to prevent a repeat of the incident. He said: “The vast majority of student work has been successfully restored and ­reinstated,” referring to the ­recovery of all student work up to Christmas 2013.

“The lost data is limited to new work saved on to the school system by students during the first half of the spring term. Some students have lost a limited amount of coursework in certain subjects.

“All work that has been completed and submitted to teachers for assessment, along with the school’s ongoing record of student ­assessment and achievement, is held elsewhere and remains secure and intact.

“The examination boards are quite clear in circumstances such as these no students will be ­disadvantaged in terms of their grade. With the help of external ­technical expertise we are i­nvestigating how this incident occurred, including why our back-up procedure failed, and the steps needed to prevent any recurrence.

“Interim technical measures have been put in place to ensure all student data is securely backed up.”