There is a Victorian schoolboy’s desk, complete with inkwell and lid, in the library of Joanne Harris’s imposing Victorian mansion near Huddersfield, West Yorkshire. It sits in front of large bay windows next to a huge antique paper press.

“I do a lot of writing in here, and this small desk is all I need because I work on such a tiny computer,” explains Harris, 41, brandishing a hardback-sized laptop. “This room catches the light beautifully in the morning but loses it in the afternoon, so it doesn’t get too hot to work in.”

Watching her type at the old-fashioned desk exemplifies the effect she and her husband, Kevin, have had on the house since they moved in nearly four years ago. Built in 1840, the six-bedroom property was extended in 1910. They have spent the past three years painstakingly updating the house while trying to keep original fittings.

“We love all the stained- glass windows and all the old wood,” she says, pointing to the fireplace in the cavernous hall, decorated with carvings of Spanish conquistadors, barley twists and mermaids. “It took us a while to get used to the clash of styles in that piece, but you’d never find a fireplace like that anywhere else. It’s unique.

“There’s a real mix of Arts and Crafts with other styles in here and, although it’s taken us a long time to restore, I’m glad we got to it before anybody started ripping out features or replacing them with something modern.”

Because of Harris’s desire to protect the panels in the parlour, she decided to forego radiators altogether in that part of the house, relying on open fires for warmth instead. Another surprise example of her conservationist streak is in the bathroom, where she shows me a 1910 cast-iron shower cubicle bolted onto the bath. The tap is marked “Wave”, “Spray” and “Plunge” in scripted lettering.

“Everybody remarks how quaint that shower looks,” she says, “but we honestly felt we couldn’t replace it with anything better.”

Born into a family of schoolteachers, Harris was raised in Barnsley by her French mother and English father. She met her husband at sixth-form college and married him in 1989. Having graduated from Cambridge University, where she read languages, Harris returned to West Yorkshire to work as a French teacher for 15 years, retiring in 1999, after Chocolat, her most famous novel, was published.

Shortlisted for the Whitbread Novel of the Year award, Chocolat was a British bestseller that became a global one after it was made into a Hollywood film. Before filming began, Harris was introduced to the French actress Juliette Binoche, who came to stay at the Harrises’ three-bedroom house in Barnsley to discuss her interpretation of the lead role. The two became firm friends and are still in contact today.

The financial success of the book quickly reached a point where Joanne was earning enough to allow Kevin to retire from his job as a land consultant for a building firm and work full-time looking after her affairs instead.

Money didn’t mean the Harrises threw caution to the winds. They waited until Joanne had written three bestselling novels before risking a move from the small home where they had lived for 10 years. In Almondbury, a village with a history going back to the Domesday Book, they found what they were looking for.

When they first saw the house, it was suffering from severe neglect. The roof was leaking, a peculiar downstairs lavatory had been bolted onto where the back door should have been, and “to say the garden was overgrown was an understatement”. But it had space (a 4½-acre garden) and plenty of rooms for their daughter, Anouchka, now 12, who occupies three bedrooms (one serves as a playroom and another as a dressing room).

The previous owners had used the house in various ways: as a small nursing home, then taking in lodgers, before turning one part into a granny annexe. The result was a mess of botched DIY and blocked entrances, and bathrooms and kitchenettes that were no longer necessary. The Harrises bought it for £485,000 at the end of 2001.

“We thought it might only take us a year, but more than three years later, the work is still not finished,” says Harris. “When your electrician has been coming to your house each day for nearly a year and sends your daughter a birthday card, you realise you must have underestimated the work involved.”

The pair have spent £270,000 restoring the property, including rewiring, replumbing, mending the roof, installing a new kitchen and decorating. The 65-year-old decorator they hired told them he’d come to the house as a boy with his father and remembered putting up the wallpaper they were now asking him to take down.

For the kitchen, they bought a retro-style Smeg larder fridge to match the old Aga, only to find a few months later that the Aga had stopped working and was beyond repair. Having started a theme, they bought new Smeg oven to match the fridge, installed hand-built kitchen units and decorated the room in 1950s colours, which suit the imposing pine dresser that came with the house.

The couple spent £4,000 restoring the garden’s fish pond, which had begun to collapse. When they dug down to repair it, they found the foundations of the original pond, built in 1840. The water fountain had sunk and had to be pulled out of a hole and reset. Now it spouts confidently, surrounded by repointed stone edging. The man who took the Aga away offered them £5,000 for the stones alone — they declined.

“We bought this house partly for the garden,” says Harris. “It will look fabulous when we have restored it to its former glory.” In the woods bordering the back lawn, the couple have begun to uncover an ornate Japanese garden designed by Thomas Mawson, the early 20th-century garden designer. When they arrived, the 100ft-long rockery was smothered by undergrowth and the Japanese acers were invisible to the eye.

The only reason the couple knew the garden was there was that it was shown on the house plans. Now the channel of rocks, which have been arranged for a high waterfall at one end, tower over stagnant ponds while the Harrises’ two regular gardeners labour at clearing weeds and gritting the moss-covered slabs. A water pump will turn it into a beautiful cascade.

“The market is a bit dead at the moment, so it’s hard to get a fix on the value of the property,” says Kevin. “But I reckon it must be worth nearly £1m, maybe more. We’re not thinking of selling, but it’s nice to know all our hard work has counted towards something.”

• Joanne Harris’s Gentlemen & Players (Doubleday, £14.99), is out now

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