It was made with transistors; many of Britain's previous experimental computers used the thermionic valve, also known as a vacuum tube.
Electronic Delay Storage Automatic Calculator (EDSAC) ran its first programs on 6 May 1949 at the University of Cambridge Mathematical Laboratory about a month after the Manchester Mark 1 was put to research work at the University of Manchester.
Computer research in the UK took place at various sites including the National Physical Laboratory in Teddington, and the RRE in Worcestershire.
Later in 1984, the Internet's engineering task force first met at RRE's successor - the Royal Signals and Radar Establishment Work in transistor technology at RRE took place in the Physics Department under Dr R.A. Smith.
Many of the early transistorised computers used valves for non-computing elements such as the power supply and clock.