The £7m fixer-upper: Britain's biggest house has 365 rooms and five miles of corridors

The sale of Wentworth Woodhouse, near Rotherham, has been agreed for £7 million, although it will take tens of millions more to repair and refurbish the country mansion.

The massive house, which is said to have 365 rooms and five miles of corridors, has had a chequered history in recent decades.

Many of its opulent rooms are now empty and most of its treasures - including the famous 18th Stubbs painting Whistlejacket - have been moved to new homes.

The house went up for sale last year following the death of owner Clifford Newbold.

Mr Newbold’s family agreed to sell to an investment company last year but the deal fell through.

Now, the Wentworth Woodhouse Preservation Trust has confirmed it has agreed to buy the mansion.

The trust has extensive restoration plans for the building over the next 15 years.

Small pre-booked tours are already run around Wentworth Woodhouse by the Newbolds, but the trust is hoping to open large parts of the property up to the public, with the help of the National Trust, and convert other sections for residential development and an events venue.

SAVE Britain’s Heritage, which has supported the trust, said the sale should be completed within three months.

In a statement, it said: “SAVE is delighted to announce that agreement has been reached with the Newbold family on the purchase of one of the finest and grandest historic houses in Britain, Wentworth Woodhouse.”

It said the £7 million cost of the acquisition has been partly funded by a £3.5 million grant from the National Heritage Memorial Fund.

The rest of the cash has come from a range of institutional and private donors.

The statement said: “SAVE and the trustees of the WWPT extend their warmest thanks for all pledges and support received.

“The long-term strategy is for the public to visit and enjoy all the most interesting parts of the property while restoring the others for revenue-earning uses such as events and holiday lets with business units in the stables.”

Wentworth Woodhouse was the northern seat of the Fitzwilliam family - one of the richest and most powerful aristocratic dynasties in England at its height.

After the family moved out 40 years ago, the building was used as a teacher training college for a time before it moved into private ownership.

The house has been ravaged by problems relating to subsidence from the coal mines beneath the park once owned by the Fitzwilliams.

The Newbold family has been locked in a multimillion-pound legal battle with the Coal Authority over compensation for the subsidence.