1970: Colour Separation Overlay (Chroma Key)

John Noakes demonstrates some of the mind-boggling visual effects that have been made possible using the Colour-Separation Overlay (CSO) technique.

Only the BBC calls it Colour Separation Overlay, by the way - feel free to call it chroma key or blue screen like the rest of the world.

This clip is from Blue Peter.

BBC Archive: Originally broadcast 28 September 1970.