A primary school which closed after a “partially collapsed” chalk mine was discovered underneath will reopen in the same site at the beginning of next year.

Pinner Wood School, in Latimer Gardens, Pinner, was shut down on March 23 by Harrow Council after staff and children were deemed to be at risk.

Geotechnical surveys undertaken by Peter Brett Associates and partner Clive Edmonds showed the ground beneath the school buildings and playgrounds could become unstable and unsafe.

Laser imaging of these previously “uncharted and unknown” tunnels revealed that they stretch beneath the school buildings and the mine roofs have collapsed in certain places.

The council has since announced that the school will return to its home buildings by January 2018 after mobilising four drilling rigs and drilling 700 boreholes over the last two months.

A spokesperson for the council, who was not named, said: “The historic mine workings underneath the school site have been identified and they are more extensive than initially thought. Some are in poor condition, with further ravelling and migrating voids discovered.

“Fortunately, our surveys show that large parts of the site are clear of any mine workings. Full laser and video scanning is almost complete.

“The joint view of the Council, our professional advisers and the school is that the underground mine workings can be filled in and the buildings made safe, permanently, in the next six months, in good time for Pinner Wood School to return home for the Spring Term 2018.”

In the Autumn Term, the whole school will be brought together to use a temporary school site at Harrow Civic Centre.

The spokesperson added: “We had considered a pop-up temporary school for Pinner Wood.

“However, with the school set to return home so soon, we now do not think we need this option for just 13 weeks of educational use, especially considering the construction risks, upheaval and expense involved.”