Harbord was appointed second in command of the 2nd Scots Guards in December 1899 and then served in the Second Boer War, arriving with his regiment in May 1900.
He took command of the 1st Scots Guards in July 1901 and was to bring them home at the war's end, leaving Cape Town on Winifredian in September 1902.
[1] For his service he was mentioned in despatches in 1901 and appointed a Companion of the Order of the Bath (CB) in the September 1901 South Africa Honours list (the award was dated to 29 November 1900[2]).
In 1914 Suffield succeeded his father in the barony and took his seat on the Conservative benches in the House of Lords.
The following year he was appointed Captain of the Yeomen of the Guard (Deputy Chief Whip in the House of Lords[citation needed]) in the coalition government of H. H. Asquith, a post he held until 1918, the last two years under the premiership of David Lloyd George.