LADY Rotherwick is enjoying a brief moment of calm before the storm.

As we speak, the first of 30,000 people are pouring through the gates of Cornbury Park – the 17th century stately home which is home to the UK’s most creative and colourful festival.

Since arriving at the rolling west Oxfordshire deer park, near Charlbury, in 2011, Wilderness has acquired a reputation for superlative music, theatre, comedy, talks and food. It is also proud of its high standards – as befits an event at one of the county’s most impressive houses.

While revellers at lesser events tuck into burgers and chips or queue for noodles, guests at Wilderness join long table banquets catered by celebrity chefs – this year including Yotam Ottolenghi, Thomasina Miers and Nuno Mendes, or drop in for breakfast at Angela Hartnett’s Cafe Murano.

Music is equally important, with headline sets by indie-rockers Two Door Cinema Club tonight, electronic artist Bonobo tomorrow, and 80s pop and art-rock star Grace Jones on Sunday. Also gracing Cornbury’s rolling acres are Michael Kiwanuka, First Aid Kit and returning reggae act Toots and The Maytals. Will Young and Laura Mvula also pop up in a musical tribute to jazz singer Nina Simone.

That Wilderness exists at all is largely down to the fun-loving Lady Rotherwick – whose enthusiasm paved the way for large scale events on the estate – part of the historic Forest of Wychwood. For eight years it played host to Cornbury Music Festival, before parting company with organiser Hugh Phillimore and instead throwing open the gates to Wilderness.

“You could say it was my passion for making the place come alive,” says Lady Rotherwick – Tania to her friends – who raised her family in the great house at the heart of the estate.

“It’s so beautiful and having a festival allows us to share that magic with other people. And the team who run it are incredible; they bring the landscape alive.”

The organising team design the festival around the landscape, with productions taking place in clearings in the woods, wood-burning hot tubs arranged around the lakeside, swimming and boating on the water, and DJ sets and acrobatics in a secret valley.

Lady Rotherwick is the festival’s greatest fan, entering the festival spirit by camping in a bell tent on the front lawn with her children. She will be joined by her 83 year-old mother, and sister Diana, and her husband Mark Carney – Governor of the Bank of England.

“Mark adores Wilderness and has not missed a single one,” she says. “My mother is also a big fan; there’s no stopping her!”

Festival-goers at this weekend’s sold-out event can also expect a healthy sprinkling of supermodels, actors, and other celebrities. Lady Rotherwick whispers a few names, and smiles: “I think it will be a star-studded line-up.”

They include a smattering of politicians, including Lib Dem leader Vince Cable, who will address the popular Forum tent, and former Home and Foreign Secretary Jack Straw.

So what makes Wilderness so special? “It is so eclectic and creative,” she says. “There’s such an emphasis on the small details – every tree and drop of water – which makes it a beautiful event.

“There is something for everyone. You can listen to lectures all weekend, like my mother, or just come for the music. And for kids its heaven. It’s incredibly safe – and quite unique.”