I just came across this delightful footage on the British Pathé YouTube channel. It shows a class of 'budding Kreislers' from 1940 learning on a special instrument designed by John Brown, with mandolin like tuning pegs to make it easier for them to tune: rather like the systems that have recently come on to the market. The bows too are designed to make it easier for children to learn the correct position. 'They are becoming masters at what is known as technique,' says the announcer.
Does anyone remember learning on one of these instruments, or having seen one? I suppose it proves that there's nothing new about innovation!