In the late 60s, with the arrival of Colour TV, the BBC was keen for something different, modern and colourful. Postgate and Firmin rolled their eyes to the sky; not in desperation but for inspiration. They discovered a small blue planet populated by pink beings known as Clangers, a green dragon who cultivated soup and orange monopods who emerged from a magician’s top hat. Wonderful and exotic creatures would often visit, and were always very welcome, especially a chicken made of iron who lived...