This week the DIY SOS team join forces with two world-famous British institutions: Great Ormond Street Hospital For Children and the Royal Horticultural Society's Chelsea Flower Show, as Nick Knowles and the team transport Chris Beardshaw's gold medal-winning garden across London and crane it over buildings and rebuild on the hospital's roof top.Despite the brilliant world-class care, there's nowhere private outside for the families to escape from the constant noise, bustle and bright lights of this huge hospital, which is why the DIY SOS team and Chris Beardshaw have taken on this hugely ambitious build. The logistics are tricky and the volunteers emotional, but they hope to offer the many brave families a bespoke, lush roof top garden as a space of calm respite.