No longer are sheds the cob-webby domain of lawnmowers and muddy boots.

The humble garden outbuilding is fast becoming a showcase for creative types to flex their interior design skills and transform a once-discarded and forgotten leftover space into something extraordinary.

Britain's annual Shed Of The Year competition has evolved out of this trend and unites enthusiastic "sheddies" from across the UK who have worked tirelessly to conjure up a themed retreat in their back gardens.

Entries over the past few years have included an American Diner-style abode complete with zinc furnishings and a jukebox, a replica ship den with deck and rigging and an abstract expressionism shed built in tribute to artist Piet Mondrian.

Some of the detail really is incredible, from a rooftop allotment with homegrown vegetables and a tin "summer bath" to a Russian summerhouse with stained glass windows and a Caribbean rum shack with its own vintage signs.

Property guru Kirstie Allsopp has long been an advocate of a shed makeover - not only for the fun of it, but also as a means of adding value to your home in a sluggish market.

"It’s a proper outside room with heating, wiring etc, and I still rate it as a really good investment," says Allsopp of her own shed office. "A garden office transforms not just how you work, but also declutters your home. Rooms seem bigger and pleasanter without a desk, office chairs, cables and computers cluttering up living space."

So if your shed is standing unused and unloved, grab a little inspiration on how to transform it - whether for work or play - with a few of Britain's best sheds, below:

The roof garden shed

Britain's most incredible sheds