Nick Knowles and the team join forces with two world-famous British institutions, Great Ormond Street Hospital for Children and the Royal Horticultural Society's Chelsea Flower Show, to transport Chris Beardshaw's gold medal-winning garden across London, crane it over buildings and rebuild it on the hospital's roof.

For hundreds of families, Great Ormond Street Hospital has become a second home. For parents that means being by their child's bedside around the clock, and for children, it results in a constant treadmill of appointments and treatments.

When Rosie was just two years old, her heart began to fail. Great Ormond Street Hospital doctors diagnosed her with restrictive cardiomyopathy, an extremely rare condition affecting just one in a million children, where the heart is too weak to pump blood. Rosie has had an operation to fit a mechanical heart while she awaits a donor, and so she needs intensive around-the-clock care with her mother consistently by her side.

Maisy has epidermolysis bullosa, known as butterfly syndrome, which is an agonising skin disorder where the body lacks the protein it needs to hold the layers of skin together, making it blistered and as fragile as a butterfly's wing. It is such a rare and serious condition that Great Ormond Street Hospital specialists have been looking after her since birth.

Despite the brilliant world-class care, there is nowhere private outside for the families to escape from the constant noise, bustle and bright lights of this huge hospital. The DIY SOS team and Chris Beardshaw have taken on this hugely ambitious build, with tricky logistics and emotional volunteers, in order to offer the many brave families a bespoke and lush calming rooftop garden as a space of welcome respite. Show less