He adopted his wife's maiden name and changed his surname by Royal Licence to Smith-Dorrien.

He was a lieutenant colonel, serving in the Hertfordshire Militia and also a captain in both the 3rd Light Dragoons and the 16th Lancers.

Smith-Dorrien was heavily involved in the restoration of the now Grade II* listed St Peter's Church in Berkhamsted, Hertfordshire, serving as the Churchwarden from 1868 until his death on 8 October 1879.

Due to his work for the church building, a stained glass window by Charles Eamer Kempe was installed and dedicated in his honour, along with a plaque.

[2] Smith-Dorrien's elder brother was Augustus Smith, Lord Proprietor of the Isles of Scilly from 1834 to 1872.