Sir Howard Frank Trayton Smith GCMG (15 October 1919 – 7 May 1996) was a British diplomat who served as Director General of MI5 from 1978 to 1981.

He was educated at Regent Street Polytechnic and Sidney Sussex College, Cambridge, where he won an exhibition to read mathematics and was a contemporary of Asa Briggs, with whom he played chess.

[1][2][3] At the outset of the Second World War he was drafted to work at Bletchley Park as a codebreaker, recommending his friend Briggs to fellow Cambridge mathematician Gordon Welchman for service in Hut 6.

[3] Returning to London, he was the Head of the Department at the Foreign Office dealing with the Soviet Union and Eastern Europe for the next five years.

[3] In 1978 Smith was unexpectedly appointed Director General (DG) of MI5, the United Kingdom's internal security service, by Prime Minister James Callaghan, serving until March 1981.