One of my favourite rooms has nothing to do with decoration, fireplaces or furniture – it’s all about the mood it creates. And although it is associated with royalty, it could not be more modest: it’s a potting shed in the grounds of Osborne House in the Isle of Wight, Queen Victoria’s much-loved home away from affairs of state.

While Osborne House itself is high Victorian, the potting shed has a sense of timelessness. It has an uneven flagstone floor, a worktop – plain wood, probably pine - that surrounds three sides of the room, with a shuttered space below for terracotta pots. There are industrial metal lights that hang from the ceiling – now ubiquitous in London kitchens, but here they are functional rather than decorative. There is also a clock on the wall, stuck at quarter to four, gardeners’ tea. In every sense, time has stood still, and I can easily imagine spending a rainy afternoon in there, pottering about with Radio 4 on in the background.

There is a deeply peaceful feeling, about something that can never be bettered, whether it's a bag or piece of furniture or an interior. It's the holy grail for so many designers. I lived in a Georgian house, which was once the rectory of Great Witchingham in Norfolk and when working on the interior, I tried to evoke a sense of warmth by paring back the clutter and selecting classic pieces, such as traditionally upholstered, comfortable sofas, layered with a mix of soft cushions, as well as using pleated lampshades and good, solid furniture. I went for things that suited the house and selected each item for a specific place, and, as with the potting shed at Osborne House, I tried to create the feeling that everything had always been there, rather than imposed recently by an outside force. These are the kind of rooms that should feel inherited.

To capture this calmness, I used pictures sparingly. The ones I used – which are in the Bonhams sale this June – are of prized cows, country landscapes and portraits of sitters who could easily have lived in the house. The furniture, such as a drum table in the garden room, is grand yet unpretentious. A leather Victorian armchair has a reassuring, time-worn presence.

When I arrived at the house, no money had been spent on it since the beginning of the 19th century, so although it was in disrepair, the bones of the building were intact. I asked Ptolemy Dean, the architectural historian, to help with the restoration and he brought such clarity and panache to the vision and the plan. Both the potting shed and Great Witchingham House have been preserved because they had been largely left alone, letting light and a few choice pieces of furniture work its magic.

Nicholas Knightly is former Design Director of Leather Goods at Louis Vuitton.

The Selected Contents of Great Witchingham House auction | 19 June - 3 July, Online, London

For enquiries, contact Charlie Thomas on charlie.thomas@bonhams.com or +44 0 20 7468 8358