Three first-edition 'Harry Potter' books found in a skip are expected to sell for thousands at auction.

Harry Potter author J.K. Rowling

Harry Potter author J.K. Rowling

Two paperback versions of J.K. Rowling's 'Harry Potter and the Philosopher's Stone' are going up for sale later this month after being discovered when a school was throwing old books away in preparation for an Ofsted inspection.

The 65-year-old owner - a teacher who didn't want to be named - saw the books in the skip and and said it ''seemed awful to throw them away''.

She added: ''I had no idea they were of any value, and neither did the school.

''They'd been well-read and the school always ensured its library was pristine for Ofsted inspections.''

The books had ended up in her loft before she realised first-edition copies sold for thousands after seeing a programme on television.

Hansons book expert Jim Spencer said: ''Hardback first editions of 'Philosopher's Stone' are as rare as hens' teeth. They're the holy grail for collectors.''