sentences:  However, the principles would be used later, as transmission became digital, in the development of digital exchanges the world over, including System X.
  
  Siemens Brothers (later taken over by Associated Electrical Industries, who renamed each section accordingly e.g.AEI Telecoms) had set up an electronic switching lab at Blackheath.This lab was headed by John Flood, who had been a founder member of Tommy Flowers' electronic switching team at Dollis Hill.