Decca made these recordings in the Kingsway Hall at a time when they were perfecting recording techniques that stemmed from an Admiralty commission to develop a hydrophone capable of detecting audio frequencies as high as 12KHz (12,000 cycles per second). Decca used their hydrophone developments to produce a moving coil disc cutter reaching 14KHz. In reproducing these recordings we have resisted the temptation to remove all the background noise, as this would compromise the original recorded sound. Most people find that after the first couple of minutes they ignore the surface noise and enjoy the performance, and these performances are entrancing.