It's the start of the fourth and final heat. Our last group of wannabe designers compete across three challenges to win one place in the quarter-final. This time they transform a bedroom each in an unusual self-build estate in south London. Hoping to fill the last spot in the quarter-final are industrial textile weaver Craig, personal assistant Nardia, furniture restorer Talie and children's author and illustrator Anne.

The designers must prove their skill in just three days, working to a client's brief with a budget of £1,000 and the help of a small team. Craig faces criticism from the start when he comes up with a bright orange colour scheme - complete with zigzag patterned fabrics - to answer a calm brief requested by his homeowners. Nardia takes on a lot of work in her bid to turn a very plain spare room into a magical woodland scheme for two young sisters, and finds she has to drop some plans. Talie faces trouble implementing an artistic Moroccan brief when her homeowners decide blue doesn't answer their request for spicy colours, and the judges fail to be dazzled by her creativity. Meanwhile, Anne struggles to deliver a decorative Japanese scheme for a nine-year-old girl.

Presenter and architectural historian Tom Dyckhoff uncovers the fascinating story of this special neighbourhood, entirely built by the original owners. It is down to the judges, though, to decide which three designers have the potential to go further and which one must leave the competition for good. Show less