Hello Michel
The button was used by the Highland Cyclist Battalion, that was their correct unit title from 1909 to 1920.
In 1908 they were known as the 8th (Cyclist) Battalion, The Black Watch and prior to that (from 1887 to 1908) they were titled the 5th (Perthshire Highland) Volunteer Battalion, the Black Watch.
As a unit I believe they seem to have remained in the UK throughout the First World War. This link will provide a little more information -
https://en.wikipedia.org/wiki/Highla...list_Battalion
Roger