If Lewis Carroll’s Alice had done up a house, she might have sought out Brendan Young and Vanessa Battaglia. The Italian-English duo have a knack for art and design that confounds expectations – and pigeonholing. In the world of Mineheart, the company they founded in 2010, nothing is quite what it seems. Tiny beaded chandeliers seem to float inside overscaled Edison bulbs that dangle from brass chains. The sitters of grand 18th-century portraits blow bubblegum, and haughty flamingos in ruffs look like fugitives from an Elizabethan menagerie.

It’s a process of filtering until we hit on something original

Like their designs, the couple enjoy the element of surprise that greets visitors to their home. Set in a tree-lined cul-de-sac of cottages and semis, from the outside it looks like a standard 1970s house – panels of weatherboarding framing wide picture windows. Inside it’s a different story. By knocking down walls and painting everything white they have conjured the illusion of a modern country cottage, with flourishes of the surreal, in the heart of Cambridge.

That ‘would work’: the kitchen island, made from an old carpenter’s workbench bought on eBay. Photograph: Rachael Smith/The Observer

The hands-on couple, who have a young son, did all the work themselves. Downstairs, one of their first tasks was to remove the wall, complete with retro serving hatch, that divided the old galley kitchen from the main living area. They found the long, rustic island on eBay. It used to be a carpenter’s workbench and they appreciate the “dents and bashes” and the deep drawer used to store tools. The white kitchen units are B&Q and Brendan’s father, a design teacher, made the sociable table from floor joists and piano legs. The dining chairs are a motley mismatch, but each one – by Thonet or Hans Wegner – has a story, as do the deep-buttoned Chesterfields, bought for “less than £16 each”, says Vanessa.

Before they moved in, the two-storey property had been rented out to students and was in a predictably awful state of neglect. They have kept the decoration simple, adding traditional panelled doors with brass handles, swapping dingy carpets for wood flooring, distressed for antique effect. The couple has always worked at home and recently added the glazed extension at the back. It doubles as studio and yoga room for sun salutations overlooking the garden. Upstairs, they painted the floorboards white and numbered the stair treads for Antoni, now five, as he learned to count.

We are family: Brendan Young and Vanessa Battaglia. They have a young son, Antoni, and a pet dog. Photograph: The Observer

As their business has grown, they have gathered a “support network” of artists who share their aesthetic. “We’ll swap ideas and images, it’s a process of filtering until we hit on something original,” says Brendan. Upstairs in the master bedroom, what appears to be a delicately painted mural of Baroque architecture turns out, on closer inspection, to be wallpaper, based on drawings by the German artist Simon Schubert. The pair of classical portraits that hangs over the bed is another illusion of digital imagery overlaid with real brushwork, as if an abstract artist had been let loose in a museum of old masters. By the bed, a table made from moulded concrete to look like petrified wood might have come from an enchanted forest.

An air of stepping through the looking glass stretches to Antoni’s bedroom. The coronet-wearing flamingo that gazes out imperiously from a black frame is a digital image by Angela Rossi – another collaborator. A Renaissance painting inspired the wallpaper of cherubs, aloft on fluffy clouds. On the back of the door, the painting of a galleon in full sail used to hang over the bath in their previous home and still has two holes, cut to fit over the taps. It is by Vanessa’s father. “He is a mathematician, but he’s painted since he was tiny. The family wouldn’t let him become an artist so he became an academic. But he still paints every day. It’s therapy for him.”

Picturesque childhood: an Angela Rossi flamingo in Antoni’s room. Photograph: Rachael Smith/The Observer

They have always used their home as a testing bed for prototypes – lighting, furniture, rugs – believing that “If we can live with them, then other people can.” The trompe l’oeil library wallpaper that launched their business began life in their last cottage. “We needed something to decorate the sitting room so we photocopied the spines of old books and stuck them on a pair of cupboards to give the illusion of wallpaper.” They sent the image to an interiors magazine who devoted a full page to the design. “We were getting orders before we’d even printed the wallpaper.”

Sustainability, too, has always been important for the couple who have a shared background of designing for large companies, including Dolce & Gabbana and Versace, until, says Vanessa: “We decided to do things that we like – even if they’re not always obviously commercial.” Now, proceeds from sales of their wallpapers are put towards a tree-planting scheme in Africa.

Mineheart, the name of their business, was inspired by Shakespeare. “We took it from the first words of sonnet 46, ‘Mine eye and heart.’ It says everything about us. We design things we’re proud to have our name on. Things which come from the heart and make us smile,” says Vanessa.

mineheart.com