Saving Country Houses with Penelope Keith

The owners of Elizabethan Pitchford Hall in Shropshire are puzzled by dangerous sinkholes on the estate, possibly caused by an extraordinary subterranean Georgian bathhouse. In Dorset, American countess Julie Mapperton is hard at work restoring Mapperton House, and Brancepeth Castle opens its doors for the annual Dragon Quest, celebrating the legend of the infamous Lambton Worm.

At Chavenage House in the Cotswolds, James Lowsley-Williams starts to rescue a derelict and overgrown pond with chainsaws, diggers and tractors. Meanwhile, in Northamptonshire, there's a dusty restoration going on at Ashby Manor House's historic gatehouse as well the restoration of the Gunpowder Plot room becomes complex, and in Wales, Sally and Hugh Martineau are preparing to host their first wedding of the season amid Treberfydd House's Victorian splendour.

At Treberfydd House in Bannau Brycheiniog (the Brecon Beacons), the biggest wedding of the year is underway, at least if the weather holds. In Shropshire, the owners of the Elizabethan Pitchford Hall are proud custodians of what is believed to be the world's oldest treehouse, supported by Britain's oldest broadleaf lime tree, which urgently needs some restoration work.

Wiltshire's stunning Iford Manor Gardens are in full bloom and a greenhouse refurbishment is underway. In Gloucestershire, an exceptional attic model railway is revealed at Chavenage, and the historic treehouse restoration project begins at Pitchford Hall in Shropshire.

Hidden secrets are unearthed at Staffordshire's Whitmore Hall. Ashby Manor's historic connections to the architect Edwin Lutyens are revealed, in both the house and in its gardens. Plus, the Chavenage mobile sauna project is hotting up.

In Chillingham in Northumberland, Britain's most haunted castle reveals its secrets as four brave visitors go on a night-time ghost hunt. The owners of Iford Manor in Wiltshire buy a pub to sell their own-brand cider in, as they seek to diversify the business. At Whitmore Hall in Staffordshire, the portraits get some long-overdue attention and a clean.

In Northamptonshire, Nova Guest has decided to get to grips with Ashby Manor's expansive parkland, and restore the views to the original vision of architect Edwin Lutyens. At Mapperton House, valuable tapestries are brought out for conservation. The staff at Chillingham Castle, Northumberland, explain the challenges of working for lifelong collector Sir Humphry Wakefield, who keeps buying new items and antiques.

In Dorset, rain and storms threaten Mapperton House's annual plant fair. In Staffordshire, the Cavenagh-Mainwaring family are dealing with leaks of their own at Whitmore Hall. Nova Guest is thrilled to sign off her summer season by inviting the first visitors in to the newly-restored Gunpowder Plot room at Ashby Manor, and at Chavenage in the Cotswolds, James and Emma are finally ready to open up their vaunted sauna project to guests.