Larmour was born in Dublin, Ireland. He attended St. Andrews College, where he played both rugby and hockey. Towards the end of his school years, Larmour focused on rugby.
Professional career
Leinster
Larmour joined St Mary's College RFC after finishing school and was in the Leinster Rugby academy . In January 2018, at the age of 20, Leinster signed him to a senior contract.[4]
Ireland
Larmour was called up to the senior Ireland squad for the 2018 Six Nations Championship.[5]
He made his Ireland debut on 10 February 2018 when he came on as a replacement in 45th minute of the 56-19 win against Italy in week two of the 2018 Six Nations Championship.[6]
In November 2018 Larmour played against Italy in Chicago. He scored 3 tries and won the man of the match award.[7]