Dougal and the Blue Cat

Dougal and the Blue Cat, called Pollux et le Chat Bleu in France, is a 1970 film based on The Magic Roundabout.

Buxton enters the ruins of the old treacle factory where he is crowned King after correctly identifying the colours of seven doors coloured different shades of blue. He recognises the first door as blue. When he enters the next room, he discovers a machine sorting out blue flowers and dumping the other colour flowers. The blue voice then says her famous line Blue is beautiful, blue is best. Im blue, Im beautiful, Im best. The second door is cobalt blue. Buxton enters a room with piles of clothing. A large machine is collecting the blue clothing and putting the other coloured clothing in a trunk. The machine also accidentally puts a blue sheet onto Buxton. Buxton correctly guesses the third door to be Saxony blue. In here, he meets an array of scary masks. Once he escapes, Buxton goes through the fourth door, which is indigo. Buxton finds himself in an observatorylike room. He finds the fifth door to be baby blue, though he momentarily forgets. He then enters the room of thunder and lightning. The next door is Prussian blue. He finds the guard room, where his blue men are created. Buxton then jumps through a small gap in between his men to reach the final door, royal blue. After being crowned, he sings a song.Meanwhile, Ermintrude is painting blue pictures. Brian inadvertently helps Dougal down from the hoist by chewing the rope holding it. Dougal then tells everyone that Buxton is evil, but nobody believes him. A blue cactus then shows up while Ermintrude is showing Buxton all her paintings. Buxton informs everyone that the cacti are the fastgrowing variety, and is happy to see it. Zebedee arrives, and informs everyone that his moustache has gone missing from his bedside table. The group search for the magic moustache, whilst Buxton sneaks off to the treacle factory. ........

Source: Wikipedia