Lord Egremont has lived at Petworth House since childhood and cares deeply about the house and park, now managed by the National Trust, and its priceless Turner collection. He talks to Angela Wintle

You could say that Lord Egremont, or John Max Henry Scawen Wyndham, 7th Baron Leconfield, 2nd Baron Egremont, to give him his full name and title, leads something of a double life. To many, he is the well-known aristocrat and landowner, whose name you will have doubtless heard mentioned in respectful tones if you have ever visited Petworth House, his 17th-century ancestral home, now managed by the National Trust and immortalised in Turner’s paintings.

But to history buffs, he is Max Egremont, the acclaimed novelist and biographer, best known for his biography of the First World War poet Siegfried Sassoon.

A quiet and thoughtful man, he has stepped from the shadows to promote his latest book, Forgotten Land, an atmospheric work chronicling the changing fortunes of the region formerly known as East Prussia.

For Lord Egremont, 63, throwing his all into the management of the 700-acre Petworth estate was never going to satisfy him. Besides, it had never been part of the plan. After reading Modern History at Christchurch, Oxford, he worked in publishing and was planning an illustrious writing career when his father’s premature death called him home.

“He was 52 when he died of cancer, which was terribly young,” he says, sitting in his handsome living room in the private south wing of the house. “I was 24 at the time and had to return here to manage the estate. It was a difficult period. While my contemporaries were carving out their careers, I had to pursue a job for which I was unsuited at that age, and I felt very cut off.

“I knew I would have to do something else. It wasn’t going to be enough, just to assume those inherited responsibilities. I felt I had to do something that was apart from that; which created a different world.”

Petworth House, built in 1688 and set in a beautiful deer park fashioned by the renowned landscape designer ‘Capability’ Brown, is home to the National Trust’s finest collection of paintings, and includes numerous works by Turner, Van Dyck, Reynolds and Blake, as well as ancient and Neo-classical sculpture, fine furniture and carvings by Grinling Gibbons.

It may seem an austere place to call home, but Lord Egremont, who has lived there since the age of five, has known little else. The family moved into the ‘big house’ in 1954 on the death of his great uncle, Charles Leconfield, who had no heirs. It was he who had bequeathed the house and surrounding parkland to the National Trust in 1947, to ensure it would be kept in perpetuity, and Lord Egremont’s father, John Wyndham, took the equally momentous decision to trade in much of the house contents in lieu of crippling inheritance tax, on condition the family remained there.

“All the Turners were traded in – I think there were 20 in all – and the Trust now looks after them for the nation,” says Lord Egremont. “I don’t regret it at all. It saved the place forever and means the things that were collected for the house will stay in the house.”

Some of the Trust’s other aristocratic tenants have admitted to mixed feelings about the organisation, but it seems Lord Egremont isn’t one of them. “I think it’s wonderful,” he says. “Perhaps I’ve been lucky, but I find the people terribly nice and they consult me on everything. There have been times when we haven’t altogether agreed, but there has to be compromise and that has always been the essence of the relationship. Likewise, the Trust feels it’s good that the house continues to be occupied, to give it atmosphere and a sense of life. After all, these houses were built to be lived in; they weren’t designed to be museums.”

Lord and Lady Egremont, who have four grown-up children, occupy a third of the house; the remainder is opened to the public five days a week during the season. But the Trust faces a continual juggling act. While it must endeavour to preserve the distinct atmosphere of the house, it also has to attract sufficient visitors to fund its upkeep. “One of the things I like about the Trust is its determination not to turn the house into a great show place with all sorts of attractions that aren’t suited to it,” he says. “It feels very strongly that people visit Petworth to see the ‘Capability’ Brown landscape and the pictures. They don’t come to see traction engine rallies.”

The Trust may be responsible for the immediate parkland, but Lord Egremont manages the rest of the estate and, once again, the biggest challenge is striking the balance between preserving the countryside and making a living from it.

But he has kept his pledge to himself and also has a tandem writing career. His first major biography was Balfour, a life of Arthur Balfour, who was Conservative Prime Minister between 1902 and 1905, and he followed it up with Under Two Flags, a biography of Major General Sir Edward Spears, a pivotal figure in Anglo-French relations during the two world wars.

Then, in 2005, came his highly-publicised authorised biography of Siegfried Sassoon, which charted the poet’s passionate and fraught relationship with the aristocratic aesthete Stephen Tennant, his marriage to the beautiful Hester Gatty and their subsequent estrangement, and his conversion to Catholicism, which brought serenity to his last decade. During his research Lord Egremont was given unprecedented access to Sassoon’s later, unseen diaries and the drafts of his autobiographies, which were more candid than his published works.

“I felt guilty at times; that I was probing into things that he would rather I hadn’t known. But he had this duality: he was a secretive man and yet he kept these endless diaries. He was shy and yet he craved recognition. I felt it was my duty to tell the truth about him.” Forgotten Land, his latest book, is subtitled Journey Among the Ghosts of East Prussia, and is his most personal yet; part travelogue, part history book, charting the troubled history of the region from 1914 until the present.

No country embodied the turbulence of 20th century European history more dramatically, he says. A great power during the 19th century, it became a free state in the Weimar Republic after1918 before passing abruptly into history when it was carved up between Poland and the USSR after the Second World War. The scene of the final battle between Hitler and Stalin, and of Stalin’s ‘terrible revenge’, it came to embody the clash of the two most significant totalitarian regimes in modern Europe.

Lord Egremont first travelled to the capital Koliningrad (formerly known as Koninsberg under German rule) in the early Nineties, when it was opened up to visitors following the collapse of the old Soviet Union. “It was incredibly bleak at that period because the Russian part had been badly neglected and had a terrible drug and Aids problem,” he says. “It had been largely destroyed at the end of the Second World War and was the victim of terrible Soviet reconstruction during the Fifties and Sixties.

“But when I returned in the early 2000s the region had been transformed – particularly the Polish part, which had become part of the European Union. It remains the poorest part of Poland, but big farming companies have moved in to work the land and there is much greater optimism. Now a member of NATO, it feels quite secure for the first time in its history because it’s no longer caught between the Russians and the Germans, as it had been for centuries.

“My book is about that change of identity and how the German people, who were thrown out after 1945, coped with the loss of their homeland, and how the Russians and Poles adopted it as their own. I met some remarkable people with astonishing tales to tell.”

Back at Petworth, Lord Egremont has his own case of changing identity; one minute the feudal heir to all he surveys, the next, the studious historian popping down to his local bookshop to collect another tome for his research.

He takes a keen interest in the life of the town and is closely involved with his parish church, St Mary’s, as well as the annual Petworth Arts Festival. Though the aristocracy doesn’t count for as much these days, he says, Petworth’s inhabitants are still “very nice” to him and he has many friends among their number.

“It’s a more natural relationship now, I think. In days gone by, almost everyone in the town worked on the estate, and that’s certainly not the case now. These days you have to prove yourself before people like or dislike you, and that’s a good thing.”

Forgotten Land: Journey Among the Ghosts of East Prussia by Max Egremont is published by Picador at �20.