Born in Edinburgh, McKay was employed in a brass foundry prior to enlisting in the 78th Highlanders in1848. He was promoted to private one year later and embarked for India, where he served at Aden, Belgaum, Bombay and Poona.
In 1854, McKay was appointed piper and was one of the first five pipers officially authorized in the regiment. He also served in:
- The Persian Campaign of 1856-57.
- The Sepoy Mutiny in India during 1857-58.
- The first relief of Lucknow.
- The defence of the Alum Bagh in September 1857.
- The reduction and occupation of Bareilly with the Rohilkand Field Force.
McKay reverted to private in November 1858. He Left India in May and was re-appointed as a piper because of a vacancy in December 1859. McKay served on recruitment duties from November 1859 to January 1860 and was discharged in April 1861.
Medal Entitlement: India Service Medal (1854-1859) with Persia clasp; Indian Mutiny Medal (1857-1858) with Lucknow and Defense of Lucknow clasps.