McKellar was born in the Parish of Craignish, Argyllshire in 1824 and was the son of Dugald and Mary (McKenzie) McKellar. He attested for the 79th (Cameron Highlanders) at Paisley in 1842 at age 18. McKellar Transferred to the 78th Highlanders in April and was promoted to corporal in October 1850. He was confined for 12 days during October 1852 and was reduced to private. In April 1854, he was promoted to Sergeant and appointed Pipe Major. He was the first officially recognized Pipe Major in the regiment.
McKellar served with the 78th in:
- The campaign in Persia in 1856-58.
- The first relief of Lucknow and the Rohilkand campaign.
McKellar was wounded in the left side by a grapeshot at the Alum Bagh. He was tried for being drunk in September 1858 and was reduced to piper for 43 days. In November, he was re-appointed to Pipe Major.
McKellar married Eliza Lorden around 1859. They had four sons and a daughter.
On March 11, 1862, McKellar was discharged to a pension of 1s 8d and went to the 2nd Lanarkshire Militia. His character was noted as "Good," though he was twice tried by Court Martial and once appeared in the Regimental Defaulter's Book. On discharge "he was allowed to reckon one year additional service for entering Lucknow."
Among his compositions were the 78th's Farewell to Belgaum, Burning of the Piper's Hut, Highland Brigade's March to Lucknow and The Barren Rocks of Aden - the latter often being attributed to others. "...[N]ot a note in it but what was composed by me. The air is mine. The name is mine. Who has a better right to give a name to a child but the father," replied McKellar when asked about its origin.
His final years
McKellar’s residences included Ballachulish, Wickham Market and Birmingham. He entered Chelsea Hospital as In-Pensioner in 1891 and died there on September 22, 1895, after suffering from bronchitis for three years. He was buried in Brookwood Cemetery, Surrey.
Medal entitlement: India Service Medal (1854-1895) with Persia clasp; Indian Mutiny Medal (1857-1858) with Defence of Lucknow and Lucknow clasps; Long Service and Good Conduct Medal. (McKellar's Good Conduct and Indian Mutiny Medals are in the Regimental Museum along with his bonnet and Pipe Banner.)