Responsible for the British discovery of radar which played a crucial role in the defence of the UK during the Second World War.

A distant descendant of James Watt, the steam pioneer, Watson-Watt had a brilliantly successful education. His first work was as assistant to William Peddie, Professor of Natural Philosophy at the University of St Andrews, and then as a meteorologist at Farnborough during the First World War.

During the 1920s he worked at the Radio Research Station at Slough, eventually becoming superintendent. He was then appointed superintendent of an enlarged radio research facility, part of the National Physical Laboratory at Teddington, in 1933. Here he was asked if radio waves could be used to destroy bomber aircraft. Calculation soon showed that this was not possible, but that radio could be used both to detect and find the distance of aircraft. A successful demonstration in 1935 led to an intensive programme of research at Bawdsey Research Station to exploit this new discovery to provide defensive cover from hostile aircraft. By 1938 the first chain of CH (chain, home) radar was working on the east coast and a reliable defence system was working by 1940.

Watson-Watt became scientific adviser on telecommunications to the government in 1940. After the war he set up a consultancy partnership to advise on industrial enterprises of all kinds and later spent some years in Canada.