He was the unsuccessful Conservative candidate at the May 1934 by-election in the Upton constituency in West Ham, and at the 1935 general election Macnamara was elected as Member of Parliament (MP) for Chelmsford. He was also joint secretary, with the Liberal MP Wilfrid Roberts, of the Basque Children's Committee.
On 11 January 1924 he joined the Territorial Army as a second lieutenant in the 3/London Regiment. He later commanded 1st London Irish Rifles, a Territorial Army battalion of The Royal Ulster Rifles and was subsequently promoted to the rank of Colonel. In December 1944 Macnamara was visiting Italy and was with 1st London Irish who were moving into the Senio Line to relieve a Gurkha battalion. Colonel Macnamara was watching men of the Battalion move up to the line in company with Major M. V. S. Boswell when a sudden German mortar bombardment fell on the area. Macnamara and Lieutenant J. Prosser MC were killed and Major Boswell was wounded. Jack Macnamara was laid to rest in Forli War Cemetery
Guy Burgess was one of his close collaborators : Burgess "In 1935, became the parliamentary assistant of a homosexual young deputy of the far Right, Jack Macnamara, a member of the Anglo-German Fellowship, an association for Nazi sympathizers. Burgess gained the confidence of MacNamara and they organized a series of sex tourist trips abroad, especially to Germany where Macnamara had ties within the Hitler Youth. Burgess managed to be in touch with a number of highly placed homosexuals, like Edouard Pfeiffer, the chief private secretary of Edouard Daladier, War Minister, an agent of the 2nd Office and of MI6. Macnamara and Burgess were invited on several occasions to pleasure parties at Pfeiffer's or to Parisian nightclubs."
- "House of Commons constituencies beginning with "C" (part 3)". Leigh Rayment's House of Commons pages. Retrieved 14 April 2009.
- London Gazette 32924
- Haileybury Roll of Honour
- Craig, F. W. S. (1983) . British parliamentary election results 1918–1949 (3rd ed.). Chichester: Parliamentary Research Services. pp. 275, 349. ISBN 0-900178-06-X.
- Stoneham Camp
- CWGC entry
- Template:A History of homosexuality in Europe : Berlin, London, Paris, 1919 - 1939, Florence Tamagne, p 91 - 92, 2004, Paris
|Parliament of the United Kingdom|
Sir Vivian Henderson
|Member of Parliament for Chelmsford
1935 – 1944