“One Sunday morning in autumn I showed Horserace to Andrew for the first time. We walked up the muddy bridle path until we found the old house sitting quietly on its own, surrounded by overgrown trees and chestnut coppice.” So begins Vanessa Nicolson’s new book, a compelling memoir that interweaves her story of growing up in an eccentric aristocratic family with the tragic death of her nineteen year old daughter Rosa. Vanessa’s beautifully written book is rivetingly, at times painfully truthful. In her words: “The memoir is about loss and motherhood… about coming from an unusual, privileged background but craving an ordinary family life.”

On the day I meet Vanessa and her husband, writer Andrew Davidson, at their house Horserace (named after the field opposite, where horses were once exercised), the woods are brimming with bluebells and nearer the house there are cherries, rhododendrons and lilac. The birds are shouting and the trees are rustling their shiny new leaves; it’s high spring, the day after Vanessa’s book is published.

An uplifting time to publish the memoir? “It’s so weird that Granta had the date of publication on 7th May, as that was the date that I was given as the due date, two years apart for both of the girls,” says Vanessa. They both missed the date, one being born later and one earlier, but the book – and perhaps the process of writing and being published could be likened to having a baby – has made its due date and is now in the world. Already some reviewers are getting the facts wrong, which is especially irksome to Vanessa, as she comes from a family of writers and documenters, people who’ve famously kept diaries, notes, receipts and letters carefully archived and filed away over lifetimes. This has proved invaluable for the checking of dates and facts, and even the state of a writer’s mind in a moment in time, giving fascinating and truthful snapshots of the past.

Horserace was built in 1862 and Vanessa and Andrew have the original bill of sale from the day Vanessa’s grandmother, Vita Sackville-West, bought the house (and later kept various ‘secretaries’ here). It is charmingly described as ‘The compact, fruitful and sporting property… built of brick and tile, with gables, covered with creepers,’ and also ‘loose boxes, corn store, range of kennels, boiling house, game rearing sheds and a substantial building fitted as a forge’ and rather poignantly at the bottom of the deed: ‘The house is let to Mr. Older at £32 a year, Landlord paying Rates on a Quarterly tenancy, and is under notice to quit.’

Vanessa inherited Horserace from her father, the art historian Ben Nicolson. She writes: “My father Ben had inherited it. He never lived there, but never sold it. He never talked about it either. I only discovered its existence when I saw him opening an envelope in London containing a rental cheque from the land agent who managed it. ‘Did you know I own a property near Sissinghurst?’ he had asked me. He said it like one would announce an old object from earlier years, a keepsake unkept. No, I hadn’t known. I was twenty then.”

Vanessa’s father died a year later and she used the house at first for weekends and holidays, gradually changing and updating it. “The basic elements were still in place; the old brick floors, the brown Bakelite light switches, the large yellow trough sink and a wood-fuelled Rayburn in the kitchen. Each of the four bedrooms contained an Edwardian basin and a small wrought-iron fireplace. Nothing had been changed for decades but that was its charm, and despite the amount of work to be done, we were optimistic,” she writes.

When their daughters were born, Vanessa and Andrew decided to make Horserace their main residence and extend the house into more of a family home. “It was gloomy and dark and surrounded by woodland,” says Andrew. “This house was badly designed for the location. The weather blows hard from the southwest and the walls are thin, porous brick and lath and plaster.

Until the 1950s, the outside was thickly painted – pink – enough to keep the house protected from the driving winter rain.” During the great storm of 1987 the house was battered and a good few trees uprooted; judging by the photos of the aftermath it looked quite scary, but fortunately Vanessa and Andrew weren’t living at the house full time. Outside this part of the house, where the wind comes whipping in across the fields, Andrew is growing smaller wind-break trees – ornamental pears, strawberry trees (Arbutus unedo) and Turkish crab apples – to replace the seventy foot oaks.

The ground floor is remarkably light and airy at present, with the open-plan kitchen at its centre. “People live so differently now,” Andrew explains. “Kitchens were always on the north side of the house in the days before refrigeration, to keep things cool. We opened it up, knocking the smaller rooms into one.” They have also added a huge picture window giving wonderful views across part of the garden.

As I look out from the kitchen Vanessa mentions that they wanted to commission a rose in Rosa’s name: Rosa Ilaria. “The gardeners at Sissinghurst were very enthusiastic and supportive, but a grower that we spoke to only wanted to name a rose Vita and were extraordinarily insensitive.” A rose named ‘Rosa Ilaria’ sounds utterly perfect as a symbol of remembrance.

As we leave the sitting room there’s debate about a chair in the corner, as to whether it’s the same chair in a photograph on the mantelpiece. In the photo Vanessa’s father Ben is sitting in the chair, his brother Nigel opposite him, both small boys, looking winsome and sweet, and their mother Vita is sitting on the arm beside Ben staring directly out at the camera from under a wonderful wide-brimmed hat. It is a beautiful shot. In the interests of historical accuracy and validation there may be a tiny difference on a horizontal bar at the base of the chair, but it certainly looks exactly the same. Did your father ever want to live here? I ask Vanessa. She laughs, “No. I don’t think he liked the countryside, or the great outdoors much. Whenever we came down to Sissinghurst he would bring a huge pile of books and hole himself away in an armchair in a corner somewhere.”

Vanessa shows me round upstairs – the first room we go into is a large bathroom. It’s painted a soft blue and I get the feeling that this is an important room, remembering also that Vanessa and Andrew first got together when he, living in places that never had enough hot water, asked if he could have a bath. “This was originally one of the bedrooms,” says Vanessa – so a generous 13’ x 13’ – “but I love baths and thought I’d turn a bedroom into the bathroom.” It is everything a bathroom should be and so seldom is; light, spacious and rather dreamy, the sort of room you could float away in.

The master bedroom is one of the few rooms in the house that’s not 13 feet square, being part of the extension. It’s a substantial rectangular room, uncluttered and restful. I notice the wardrobes along one wall of the room, painted in a light green, each panel decorated with a simple sprig of wild flowers. “They were painted to match the Florentine cabinet downstairs in the dining room, but with a less ornate treatment,” Vanessa explains.

The room that was Rosa’s is simply furnished and above the fireplace on the wall there are picture frames containing some of her things. In the centre is the butterfly skirt that Vanessa writes movingly about in her memoir. Skirts feature a few times in the book – there seems to be a symbolic trinity of them, representing (in my mind) Vanessa, her mother and Rosa; there’s the innocent, almost ephemeral butterfly skirt (now pinned within a frame as is often the fate of butterflies), a very striking, sophisticated geometric skirt that is almost a work of art in itself, that Vanessa’s mother Luisa is pictured wearing in the fifties, and a ‘coming of age’ brown suede mini skirt (with matching fringed bag) worn by the teenaged and, at the time, increasingly rebellious Vanessa.

The garden at Horserace has inevitably been hugely influenced by Vanessa’s grandmother Vita. Much of the original layout is hers and Andrew spent a long time studying her writing before planting. “The structure here reflects her style – there was still lots of fiddly box hedging running along the paths,” he says. The section of garden closest to the house is divided into quadrants, each planted with an Irish yew, as at the castle, which Andrew has repeated on the other side of the house nearest the kitchen, but using Sorbus hupehensis within each square. “I’m trying to develop a system of encouraging lots of invasive but nice plants to challenge the existing, aggressive weeds. It’s a large garden for one person and Andrew manages it on his own, adding resignedly “even if I had a team of five gardeners, we’d still get thistles in here.”

Weeds and wild plants can creep in from all around, as the house is surrounded on three sides by woodland and on the remaining one by open fields. But Andrew also likes to encourage the garden to leach out into the woods, blurring the boundary between the house and the beyond. It’s fun to see the odd blousy and exotic looking rhododendron or camellia trying (and joyously failing) to blend into the demure green and brown of the woods.

Andrew is a plant collector; among his plants is an assortment of 15 camellias inherited from an uncle, several acers in the ‘autumn’ garden, an Italian privet that was found as a seedling on Luisa’s roof terrace in Florence and some rocket-shaped Italian cypresses, planted for Vanessa to remind her of Italy – “I thought she would like them, but she doesn’t!” he laughs.

We walk through the orchard containing apple, pear, quince and Vita’s favourite cherry, Prunus ‘Pandora’, out into the wilder garden and start of the wood past the old forge, rebuilt in order to keep a building in its position and back around to where we started.

On the ground floor in Vanessa’s office, where she writes, there’s a small shrine to Rosa, including a tiny picture of the patron saint of people who died young. “Writing the book has focussed my feelings. I wanted Rosa to exist properly,” says Vanessa. Now Rosa is truly documented into time. She has her place and cannot be erased. A rose may eventually be named after her, but regardless, she will always be Rosa Ilaria.

As we leave, the last paragraphs of Vanessa’s memoir rattle round in my head: “Here I am still at Horserace, the house I both love and hate, where you (Rosa) were conceived and where you died… we are always talking about leaving, but I am sure we shall be here for a very long time.”