Felton was brought up in a staunch Primitive Methodists household. Her mother Una Page (née Bone) wrote temperance hymns, and her father was a Primitive Methodist minister. She studied at the University of Southampton and was later awarded a PhD at the London School of Economics; she was later appointed to its board of governors.
From 1947 to 1951 she served as the first Chairman of the Corporation for the construction of the new town of Stevenage.
During the late 1930s, Felton became a leading urban planner, connected to the London County Council where she worked until the start of the Second World War. During the war she worked for the British Ministry of Supply. During the war and afterwards, Dr. Felton lectured on urban planning and housing for the BBC Home Service and BBC World Service.
After the war hundreds of thousands of new homes were being built. Dr. Felton was closely involved in the planning and implementation involved. In the years 1945–1946 she was part of the major New Towns Committee, led by John Reith. She worked for the London County Council and Hertfordshire County Council.
In 1949, Felton became chairperson of the Stevenage Development Corporation in the county of Hertfordshire. Stevenage was the first of the post-war new towns that were built by the Labour government on the basis of the New Towns Act of 1946. she held the post for just two years (see below).
In 1951, Felton visited North Korea as part of the Women's International Democratic Federation commission and outlined her impressions in the book That's Why I Went (1954), adhering to an anti-war position. After her visit to Korea she was fired from her job as Chairman of the Stevenage Development Corporation, expelled from the Labour Party and threatened with prosecution for treason.
In 1953 Felton became a member of the World Peace Council. Winner of the International Stalin Prize "for peace between peoples" (1951).
In 1952, Felton chaired the inaugural meeting of the National Assembly of Women at St. Pancras Town Hall in London. Issues vocalized in this meeting included condemnation of the Korean War and support for disarmament.
In 1956, whilst attending a forum in India, Felton met with Rajaji, an Indian lawyer, independence activist, politician, writer and statesman, and also the last Governor-General of India. She later wrote his biography, I Meet with Rajaji (1962).
- "FELTON, Mrs Monica". Who Was Who. Oxford University Press. 2014. Retrieved 26 July 2015.
- W Eric Jackson (1965). Achievement: A short History of the London County Council. Longmans. p. 262.
- "We Accuse! Report of the Commission of the Women's International Democratic Federation in Korea". Internet Archive. Retrieved 2016-02-28.
- J. Newsinger, "Much to Be Modest About", New Left Review 108, Nov-Dec 2017.
- Tebbs, Betty. A Short History of the National Assembly of Women. Manchester, UK: National Assembly of Women, 1993.