Hundreds of pupils will not be able to move into their new schools in September because of construction delays blamed on the weather.

Students at Marriotts comprehensive, and Lonsdale – a school for children with special needs, both in Stevenage, were due to begin classes in new buildings on the Marriotts’ Telford Avenue site at the start of the new academic year but will now not be able to move until January.

Builders Balfour Beatty blamed the “recent extremely wet weather and complexity of the construction programme” for the delay in the �8.7m project, education authority Herts County Council said.

An employee of Lonsdale School, who wanted to remain anonymous, said staff and parents were only told two weeks ago.

“All the staff have had to pack up and unpack,” he said. “People didn’t know what was going on.

“It’s a massive move - everyone preparing themselves for it and now it’s delayed.”

Frances Button, cabinet member for education and skills at County Hall, said the authority wants to get staff and students into the new buildings “as soon as possible when we are satisfied that the building works are completely finished.

“The hand-over of the new buildings to the schools will now take place in December, which will allow for moving during the Christmas holidays rather than during term time with minimum disruption to pupils and their families.”

As a Private Finance Initiative the council will only start to pay for the building once it is in use, she added.

A second � �5.6m Balfour Beatty Stevenage project to redevelop Nobel School was completed this week, with new buildings ready for September HCC said.

The authority would not confirm whether there had been a financial penalty imposed on Balfour Beatty for the delay.