Scantlebury worked with Keith Bartlett at the National Physical Laboratory in south-west London, in collaboration with the National Research Development Corporation. His early work was on the Automatic Computing Engine and English Electric DEUCE computers. Following this he worked with Donald Davies on his pioneering packet switching concepts. In October 1967, he attended the Symposium on Operating Systems Principles in the United States, where he gave an exposition of packet-switching, developed on the NPL Data Communications Network. Also attending the conference was Larry Roberts, from the ARPA; this was the first time that Larry Roberts had heard of packet switching. Scantlebury persuaded Roberts and other American engineers to incorporate the concept into the design for the ARPANET. Scantlebury is one of the first people to describe the term protocol in a data-communications context in an April 1967 memorandum entitled "A Protocol for Use in the NPL Data Communications Network" written with Keith Bartlett. He was part of a team that developed the alternating bit protocol in 1969. Along with Donald Davies and Derek Barber he participated in the International Networking Working Group from 1972, initially chaired by Vint Cerf. He was acknowledged by Bob Kahn and Vinet Cerf in their 1974 paper on internetworking, "A Protocol for Packet Network Intercommunication", and he co-authored the standard agreed by the INWG in 1975, "Proposal for an international end to end protocol". Later, as head of the data networks group within the Computer Science Division, he was responsible for the UK technical contribution to the European Informatics Network, a datagram network linking CERN, the French research centreINRIA and the UK’s National Physical Laboratory.
Logica
He joined Logica in 1977 in their Communications Division, where he worked on the CCITT X.25 protocol and with the formation of the Euronet, a virtual circuit network using X.25. He moved to the Finance Division in 1981.
Personal life
He married Christine Appleby in 1958 in Middlesex; they had two sons in 1961 and 1966, and a daughter in 1963. He lives in Esher. Scantlebury was influential in persuading NPL to sponsor a gallery about "Technology of the Internet" at The National Museum of Computing, which opened in 2009.