Born in Wales, he started work in a factory aged ten, but studied in his spare time and won a scholarship to University College Nottingham. He was ordained as a Baptist minister in Warrington and Liverpool, and became president of the Liverpool Free Church Council.
A committed socialist, he was elected at the 1922 general election as Member of Parliament (MP) for Consett. From 1929 to 1931 he was Deputy Speaker of the House of Commons, and Chairman of the Ways and Means Committee.
Dunnico also holds the distinction of being the Labour Party's first backbench rebel, when on 21 February 1924 he became the first Labour MP ever to vote against a Labour government. The vote was on the First Labour Government's programme of building light cruisers, to which Dunnico (a former secretary of the Peace Society) objected because he feared the start of an arms race, and because believed that the Parliamentary Labour Party had not been properly consulted.
At the 1931 general election, he was defeated in Consett by the Liberal National candidate John Dickie. In January 1935 Dunnico announced that he felt it his duty to support the National Government because he felt political partisanship was damaging to the national interest. He was National Labour candidate at Wednesbury at the 1935 general election but narrowly failed to win election.
Dunnico was involved in founding an unusual masonic lodge, the New Welcome Lodge No. 5139, which was consecrated in 1929, shortly before the formation in 1929 of the second Labour Government. It was created at the suggestion of the then Prince of Wales, afterwards King Edward VIII, who was concerned by the antagonism between Freemasonry and the British left towards Freemasonry. The New Welcome Lodge was intended to form a link between Freemasonry and the new governing party, and was open to Labour MPs and for employees of trade unions and the Labour party; its members included Labour's deputy leader Arthur Greenwood. However, when the Parliamentary Labour Party was reduced in strength after its split at the 1929 general election over Ramsay MacDonald's formation of the National Government, numbers were reduced, and in 1934 membership was opened to all men working in the Palace of Westminster. Dunnico was Master of the New Welcome Lodge in 1931.
From 1947 to 1953, Dunnico was president of the Essex County Football Association.
- Obituary in The Times, Saturday, 3 October 1953; pg. 8; Issue 52743; col E: "Sir Herbert Dunnico Social Reformer And Churchman" with portrait.
- OBITUARY in The Manchester Guardian; 3 October 1953
- Historical list of MPs: C, part 5, at Leigh Rayment's Peerage Pages
- Body without soul: The Philosophical Outlook of British Freemasonry 1700-2000, by Professor Andrew Prescott. Published by The Cornerstone Society
- Founder of the awkward squad, This is North East, 5 November 2005
- Craig, F. W. S. (1983) . British parliamentary election results 1918-1949 (3rd ed.). Chichester: Parliamentary Research Services. ISBN 0-900178-06-X.
- International Peace Society Records, 1817-1948
-  He is listed as the Secretary of the International Peace Society in the 1921 edition of the Labour International Handbook]
- Cowley, Philip (15 March 2007). "The more things change …". The Guardian. Retrieved 2007-08-14.
- Philip Cowley and Mark Stuart (2007). "Trident record breakers?" (PDF).
- "Labour Leader And National Unity", The Times, 28 January 1935, p. 14.
- "The Mason's candidate New Welcome Lodge No.5139 and the Parliamentary Labour Party" by John Hammill and Andrew Prescott (2006) in Labour History Review, Vol. 71, No. 1, April 2006
- London Gazette, Issue 34469 published on 31 December 1937. Page 2 of 22
- Essex County Football Association: Past Officers
- Hansard 1803–2005: contributions in Parliament by Herbert Dunnico
|Parliament of the United Kingdom|
| Member of Parliament for Consett
John Purcell Dickie