The regiment was formed on the creation of the Territorial Force in April 1908 and placed under orders of the London Mounted Brigade. It was based at 39 Finsbury Square. Its Volunteer Force predecessor had been formed in 1901 for service in the the Boer War and had originally been titled the 20th Imperial Yeomanry.
1/1st City of London Yeomanry
- August 1914 : moved with the brigade to Hounslow and then to join 2nd Mounted Division at Streatley.
- November 1914 : moved with brigade to North Walsham.
- April 1915 : moved to Egypt.
- August 191 5: dismounted and moved to Gallipoli.
- December 1915 : returned to Egypt and remounted.
- January 1916 : Division broken up; brigade moved to Suez Canal Defences and renamed 8th Mounted Brigade.
- November 1916 : moved to Salonika.
- June 1917 : returned to Egypt; brigade under orders of Yeomanry Mounted Division (21 July).
- 7 April 1918 : left brigade and formed ‘E’ Battalion Machine Gun Corps with 1/3rd County of London Yeomanry.
- 1 June 1918: landed at Marseilles for service in France. Moved initially to Etaples.
- 17 August 1918: renamed 103rd Battalion MGC.
2/1st City of London Yeomanry
- Formed in September 1914 as a “second line” (training, draft-supplying reserve) for the 1/1st. Came under orders of the 2/1st London Mounted Brigade.
- March 1915 : moved with the brigade to East Dereham and placed under orders of 2/2nd Mounted Division.
- 20 March 1916: division renamed 3rd Mounted Division.
- April 1916 : brigade renamed 12th Mounted Brigade.
- July 1916: converted into a cyclist unit, under orders of 4th Cyclist Brigade in 1st Cyclist Division at North Walsham.
- November 1916 : division broken up; merged with 2/1st West Somerset Yeomanry to form 5th (West Somerset and City of London) Yeomanry Cyclist Regiment. Moved to Littlebourne in Kent and came under orders of 5th Cyclist Brigade in new 1st Mounted Division.
- 4 September 1917: division renamed The Cyclist Division.
- By January 1918: moved to Wingham in Kent and then remained there.
3/1st City of London Yeomanry
- Formed in 1915 as a “third line” (training, draft-supplying reserve for the 1/1st and 2/1st).
- 1916: affiliated to 6th Reserve Cavalry Regiment at Dublin.
- Early 1917: absorbed into 1st Reserve Cavalry Regiment at the Curragh.
In the 1917 renumbering of the Territorials, the City of London Yeomanry issued numbers from the block 260001-265000. Corps of Hussars.
There is a memorial to the regiment in St Bartholomew the Great Church, Smithfield Names