126th Baluchistan Infantry

Known as the 26th Regiment of Bombay Native Infantry in the Bombay Army
Known as 126th Baluchistan Infantry in the Indian Army

Chronology

10th Baluch Regiment tie pin

126th Baluchistan Infantry Wikipedia
126th Baluchistan Infantry British Empire website
10th Baluch Regiment Wikipedia
10th Baluch Regiment Defence Journal Karachi June 1999, now archived. Probably an extract from Sons Of John Company by John Gaylor
History of The Baloch Regiment 1820-1939 The Colonial Period Defence Journal Karachi October 2000, now archived.
History of The Baloch Regiment 1939-1956 Defence Journal Karachi November 2000, now archived.
"The British Campaign in Aden, 1914-1918" by Mark Connelly Journal of the Centre for First World War Studies Vol. 1, No. 3, 2005. pages 65-96, now an archived webpage. Includes brief mention of the 126/Baluchistans.
"Military Operations in Aden 1914-1915" by Harry Fecitt, from Harry’s Sideshows kaiserscross.com. Includes mention of the 126th Baluchistan Infantry.
"Kurdistan 1919: Military Operations in Mesopotamian Kurdistan: South Kurdistan, May–June 1919" by Harry Fecitt. From Harry's Sideshows kaiserscross.com
Image 26th (Baluchistan) Regiment of Bombay Infantry. artnet.com. Originally from Types of the Indian Army: Illustrating the Races Enlisted in the Bengal, Punjab, Madras & Bombay Armies by Frederick Bremner Quetta 1897. Derived image commons.wikimedia.org

Footnote, page 52 The Bombay City Police: A Historical Sketch 1672-1916 by S M Edwardes 1923 Archive.org. States that in the 1870s and 1880s, the 26th Bombay N I was known as the "Black Watch" owing to it having three Eurasian British Officers, including John Miles the Commandant.