Ronald Charles Grant, 10th Baron de Longueuil

Ronald Charles Grant, 10th Baron de Longueuil (13 March 1888 – 12 July 1959) was a British soldier and peer. He was born in Pau, France, the son of John Moore Charles de Bienville Grant. He married Ernestine Hester Maud Bowes-Lyon, daughter of the Hon. Ernest Bowes-Lyon and Isobel Hester Drummond, on 4 October 1918. He was educated at Elizabeth College, Guernsey. He was in the French Foreign Legion and was a civil engineer.

He succeeded to the title of Baron de Longueuil on 17 October 1935. He fought in the Second World War as an officer in the service of the 3rd Battalion, King's Own Yorkshire Light Infantry. He died in Navarrenx, France in 1959.