Roberts was born in Birkenhead, the son of Frank Roberts, a civil engineer. He attended Brighton College and Pembroke College, Cambridge.^[4] During World War I, he served as a lieutenant in the Suffolk Regiment and was wounded in the Third Battle of Ypres.^[5]

He was Secretary of Cambridge University Press from 1922 to 1948, Master of Pembroke College, Cambridge from 1948 to 1958, Vice-Chancellor of University of Cambridge from 1949 to 1951, and Chairman of the British Film Institute from 1952 to 1956. He was an author, publisher and biographer and a noted Sherlockian, being president^[6] of the Sherlock Holmes Society of London. According to Jon Lellenberg, Roberts is responsible for the popularisation of the Sherlockian game of criticism.^[7]

In 1954 he held the Sandars Readership in Bibliography and his topic was "The evolution of Cambridge publishing.^[8]

He was knighted in 1958.^[9]

The National Portrait Gallery holds three photographic portraits of Roberts by Elliott & Fry, made in 1949.^[10]

He married, firstly, Irene Wallis (died 1932), daughter of Arnold Joseph Wallis, Fellow of Corpus Christi College, Cambridge. They had two daughters and a son. After her death, in 1938, he married a second time to Marjorie Dykes, widow of Dr Meredith Blake Robson Swann. Roberts was stepfather to Hugh Swann,^[11] cabinet maker to Queen Elizabeth II, and of Michael Swann, former chairman of the BBC.

He died in Addenbrooke's Hospital in Cambridge.^[3]

1. A Picture Book of British History; Cambridge University Press, 1914
2. The Story of Doctor Johnson: being an introduction to Boswell's Life; Cambridge University Press, 1919
3. A History of the Cambridge University Press 1521–1921; Cambridge University Press, 1921
4. Doctor Johnson In Cambridge: Essays In Boswellian Imitation; Putnam, 1922
5. Lord Macaulay: The Pre-eminent Victorian; Oxford University Press, 1927
6. The charm of Cambridge; A & C Black, 1927
7. An Eighteenth-century Gentleman and other essays; Cambridge University Press, 1930
8. Doctor Watson: Prolegomena to the study of a biographical problem; Faber & Faber, 1931
9. Introduction to Cambridge; Cambridge University Press, 1934
10. Pembroke College, Cambridge: a short history; Cambridge University Press, 1936
11. Zuleika in Cambridge; Heffer & Sons, 1941
12. Springs Of Hellas And Other Essays, with Memoir by S.C. Roberts, Cambridge University Press, 1945
13. British Universities (Britain in Pictures); Collins, 1947
14. The Sir Walter Scott Lectures for 1948; Oliver and Boyd, 1948
15. Sherlock Holmes: Selected Stories: with an introduction by S C Roberts, Oxford University Press, 1951
16. Holmes & Watson: A Miscellany (Otto Penzler's Sherlock Holmes Library); Oxford University Press, 1953
17. Samuel Johnson; Longmans, 1954
18. The Evolution of Cambridge Publishing; Cambridge University Press, 1956
19. Doctor Johnson, and others; Cambridge University Press, 1958
20. Edwardian Retrospect; UK English Association, 1963
21. Adventures with Authors; Cambridge University Press, 1966
22. The Further Adventures of Sherlock Holmes: The Adventure of the Megatherium Thefts, Penguin Books 1985

• Works by Sydney Castle Roberts at Project Gutenberg