Now you see it, now you don't: from sofa beds to convertible tables — the best flexible furniture for small spaces

While the nation has been getting fatter, Britain’s new-build homes have been shrinking — down a third in size since the Seventies according to LABC Warranty, which certifies the square footage of new homes.

Today, adds Ikea, UK homes have the smallest floor area of any European country, at an average 85 square metres.

New homes now average just 76 square metres, with some office-to-home conversions as tiny as 15 square metres. Recent proposals for “micro homes” have suggested floor spaces of 20 to 40 square metres.

No wonder finding ways to save and enhance what space you have is a priority for many Londoners.

Neat, multifunctional furniture is obviously useful, says Kate Butler, Habitat head of design. Top of the list are convertible sofa beds and stools.

“But also use visual tricks,” she adds. “Skinny frames let light flow around a room, as does an armless sofa on legs. Glass-topped tables and light woods have an airier feel. Metallic finishes and mirrors bounce the light around.”

Place a mirror opposite or at right angles to a window or behind a table lamp — try several in the same room.

Vertical lines add a feeling of height, so try a striped wallpaper or a strip of colour, or a tall mirror or narrow shelving unit. Clear clutter into baskets or boxes. Keep at least one shelf of a unit empty to display a single item, such as a vase of flowers.

Author and stylist Joanna Thornhill has space-enhancing tips for old homes. She lives with her partner Paul in Walthamstow and says their home — displaying an ingenious mix of furniture finds, personal treasures and pretty colours — is “typically Victorian, cramped and poky”.

Her most recent book, My Bedroom is an Office & Other Interior Design Dilemmas, is crammed with down-to-earth Q&As (Laurence King, £14.99).

Thornhill says to keep walls, woodwork and ceiling the same colour. “Don’t define different zones, just add accents for contrast. And paradoxically, think big. Go for the largest sofa that will fit, maybe an L-shape, rather than a collection of small chairs. Throw down a generous rug underneath it and have large statement artworks.”

Get stuff off the floor and on to walls using simple fitted shelving. Do it yourself if you are confident. Measure up, get wood cut to size in a builders merchants or a store and buy brackets — or it’s a simple job for a handyman.

Across town in Chelsea, interior designer Katharine Pooley uses drawers under beds and creates shallow recesses between pipe runs in bathrooms. If you have a hallway cupboard, turn the space into a study spot with pull-out chair. Bunk beds are a given for children sharing rooms. Get toys and books off the floor.

Create storage under the stairs and add bookshelves to landings and above doors. Invest in a slimline TV and bracket it to the wall. Organise space inside cupboards and wardrobes with double hanging racks, racks that swing down and baskets that clip on to shelves.

Some sofas won’t even fit up the stairs, or through a door. Argos can deliver a chunky Remi two-seater in two boxes for easy self-assembly for just £249.99. Sleeker is the just-launched Snug Shack sofa. This arrives in a single box, costs £899, delivered free within three days. You can put it together in three minutes, say its creators, father and son Robert and Peter Bridgman.

Well-planned fitted storage is a boon but usually pricey. Cutting costs, Guildford-based DIY Alcove Cabinets makes furniture to measure, delivered flat-packed for you to fit and finish. Prices start from £390 for an alcove dresser.

The Futon Company brought those now ubiquitous floor mattresses to London’s nomads over 35 years ago, but its main focus now is saving space. “That’s what our customers ask for over and over,” explains founder-director Robert Pearce.

Coming shortly are three winning designs from the company’s Small Space Furniture Awards, a competition held for recent graduates. Being protoyped in London and China are a roll-up bed that turns into a coffee table, by RCA graduate Riku Toivonen; neat wall-mounted storage cubes in solid oak by Sophie Taylor, who studied at Kingston, and solid peg-fixed adjustable shelving by Michael Buick, a graduate of Rycotewood Furniture Centre in Oxford.