it is a name that walks into a room before you do,” acknowledges Hannah Rothschild. She’s right; it may be a Zoom room but before we speak I know far more about her ancestors than I would with most interviewees.

Rothschild, an author, filmmaker and philanthropist, is the eldest daughter of Jacob Rothschild, the fourth Baron Rothschild, and a descendant of Baron Edmond James de Rothschild, who laid the groundwork for much of what would become the state of Israel.

Coming from such a famous family may explain how she came up with the premise for House of Trelawney, a biting, gossipy satire about an aristocratic dynasty crashing and burning amidst the 2008 credit crunch, which is out in paperback this week. It is Rothschild’s third book; The Improbability of Love won the 2016 Bollinger Wodehouse best comic novel gong.

The very English Trelawneys, who can trace their Cornish roots back 800 years, are not the Rothschilds, but their creator has a love for family sagas, stemming less from her extraordinary lineage, and more from being part of a very close clan. “I spend an inordinate amount of time with my children and my father and my cousins. That’s just how I live and how I relate.”

The Trelawneys are encumbered by their history and the pressure to maintain their sprawling, but crumbling, stately home. It’s a way of life Rothschild thinks is going extinct. “The aristocrats’ time has gone,” she says. “Perhaps the only people who really believe it’s still there are the aristocrats.”

Sympathising with the privileged few during a recession is a hefty ask of readers, but Rothschild is rather protective of her protagonists. “They are literally trapped by their lack of imagination about how to live a different life. They didn’t see an alternative to living in Trelawney, as romantic and beautiful as it is, even though it was destroying them and their future.”

As a woman, Rothschild was never in line to become the next baron, but she is familiar with living with the weight of expectation. “When I was young, I did find it very hard. There were people who had quite clear preconceptions about who I was or how I would behave,” she admits. “It’s a huge name.”

She felt pressure particularly to meet the legacy of her distinguished forebears, both distant and not so distant. She has written a biography of her aunt, Baroness Nica, but mentions specifically her great aunt Dame Miriam, a distinguished scientist, and her historian aunt Emma. But worries about meeting up to “an illustrious heritage” lessened as she built her own career, first in film and TV, and them as the first female chair of the National Gallery’s board. Now, she says, “I feel not that I live up to it, but I know who I am.”

She briefly considered a pseudonym, but was well aware of the benefits the surname brought. “There are huge advantages, it would be ridiculous to say there aren’t. It comes with a glorious history and packs a punch, so I’m not going to say poor me,” she laughs.

The downside is that the family continue to be the target of “crazy conspiracy theories” and antisemitic cranks convinced the Rothschilds are among a powerful Jewish cabal.

“If only we had that power,” she jokes. “I say ‘if only’ but I don’t want that kind of power. But you think ‘what world are you living in?’ It’s really baffling. I’m a fiction writer so I can absolutely go into the realms of absurd, but I do think this is beyond absurd.”

Dealing with such attacks doesn’t get easier, she says, especially when she sees trolls going after her children (she has three daughters with her former husband, William Lord Brookfield). She thinks online anonymity is the problem. “Until Twitter and Facebook and everyone else get their act together you will get people who feel they can say anonymously whatever they think.”

A close friend of Rabbi Julia Neuberger, Rothschild occasionally attends synagogue, although her engagement with Judaism is more spiritual than day to day. But in normal times she visits Israel five times a year in her capacity as chair of the family foundation, Yad Hanadiv.

She first went at 17, although most teenagers’ tour experience doesn’t include travelling with Isaiah Berlin and Teddy Kollek. Her main impression was of the music on kibbutzim — “each one seemed to have its own orchestra” — and of bad food. Beyond that, she felt it was “like the bible vivified… the wilderness really looked like that. It was a much less sophisticated place, it’s fair to say. I’ve seen extraordinary changes over 42 years.”

Going round the Knesset or the Supreme Court, both funded by the family, gives a tremendous sense of pride, but Rothschild feels removed from the family’s legacy there. “Israel has obviously necessarily moved a long way from the original vision of Baron Edmund. And the Israelis don’t treat us as special. I still get stopped at the airport every time.”

She remains avowedly apolitical when it comes to Israel, saying that if you’re doing philanthropic work, “by and large you can stay outside the political arena”, although the flux and lack of national budget has been challenging for Yad Hanadiv.

The foundation is, like many charities, focused on the pandemic response, although programmes continue around education and employability, particularly for Israeli Arabs. Yad Hanadiv is currently funding the development of the National Library in Jerusalem, as well as working on an environmental project to restore the Tzipori river, which runs through Arab, Jewish, Druze and Christian areas. “I think it’s an amazing metaphor for Israel and for bringing together lots of different communities.”

Rivers and their crossings are an important part of Rothschild’s life, and have been for a decade, when she found herself inspired by David Beckham’s speedboat ride down the Thames for the Olympic opening ceremony. It occurred to her what an untapped resource the Thames and its bridges was.

“It is our liquid history, London is founded on the river, its success is because of the river, but the bridges have just become something to go over or under,” she says. “Each of the bridges have such an extraordinary history, for example Waterloo was built by women in the war, and Vauxhall is the arts bridge. It’s a riveting history.”

This planted the seed of an idea to create a continuous artwork illuminating and uniting the bridges. Nine years on the project, created by artist Leo Villareal after a global search, has sparked into life. Already the nine bridges between London and Lambeth bridges have been lit; more is to come.

The process has been fraught, involving reams of paperwork and 50 public bodies. “One side of a bridge is owned by one council, the other side by another, and the middle is by somebody else and then the water underneath it is another public body, and the lighting is another one,” she says. Along the way, there have been setbacks; they were about to start lighting at Cannon Street bridge when a rare Egyptian goose started laying eggs beneath and the RSPB put the project on hold. Under another they discovered a rare sea cucumber, scuppering work.

Now it’s live, she says “it’s a ribbon of light running through our city”, a Covid-friendly artwork that makes the bridges a draw and, she hopes, makes the areas around them safer. “It’s bringing a lot of positive activity after dark to the core of our city.”

She has watched with sadness as the pandemic has badly hit cultural life, and is aware there are challenging times still to come. Nevertheless, she is optimistic. “I believe very passionately in the arts’ ability to reinvent itself and to find new ways of expression,” she says.

That matters, she says, because artists will be the ones to make sense of this turbulent year we’re had. “None of us yet know what post-Covid life is like. We will need the artists and writers and philosophers to guide us through.”

Having written a novel about the credit crunch, might Rothschild try her hand at a pandemic novel? In fact, she has already started on a sequel to Trelawney, and is working on a non-fiction book involving Second World War diaries.

“I had to have ten years to write Trelawney,” she says. “I want to write about Brexit and the pandemic, and I think again I may need to leave a bit more time to really be able to stand back.” Even if we have to wait a decade, it will be worth it.

House of Trelawney is published by Bloomsbury in paperback this week