J. C. S. Macgregor was the son of an Aberdeen University professor and a 'son of the manse'. He was educated at Edinburgh University and Trinity College, Oxford.
He joined the staff of the BBC's Edinburgh relay station, 2EH, on 5 October 1925, becoming director of that station in March 1926 after the transfer of George Marshall to the Glasgow station 5SC. Macgregor followed him to Glasgow in 1930 when he became station representative there.
He moved to London as an announcer. When, in 1934, the size of the News staff was greatly increased and a separate News Section was started inside the Empire and Foreign Services Branch, Macgregor was given the post of Empire News Editor and created a Section which, by 1940, had grown into a large Overseas News Deparment, serving not only English-speaking audiences in the Empire but foreigners in all parts of the part.
Ahead of the Second World War, Macgregor was one of 38 people seconded from the BBC to the Ministry of Information and he served there from August 1939 to 1942.
He returned to the BBC in September 1942 as Assistant Controller of the News division at head office. From October 1947 he succeeded A. P. Ryan as News Editor, when the latter decided to resume his career in newspapers. This promotion put Macgregor in charge of all the BBC news except the European service.
- 'Scots at the BBC', Press and Journal, 10 March 1943, 4.
- Ariel, June 1937, 34.
- Briggs, Vol II, 145.
- Briggs, Vol III, 79.
- See BBC WAC, R28/227.
- 'Glasgow man's appointment', Glasgow Herald, 18 August 1947, 2.