The Army List of 1885 says he served in the First Boer War in charge of the Mounted Infantry.
He is mentioned in the book by Charles Norris-Newman called 'With the Boers in the Transvaal and Orange Free State in 1880-1' (
archive.org/details/withboersintrans00norr
)
p153.
Many special service officers were also despatched, most of whom had already seen service in South Africa. Prominent among these were. Major Barrow, 19th Hussars, who brought with him a properly organized squadron of irregular cavalry and mounted infantry force. Colonel Buller, V.C., C.B., Colonel Herbert Stewart, and many others.
p164.
The Hankow had arrived at Durban on the preceding Thursday, bringing a wing of the 6th Dragoons, Barrow's Mounted Infantry, some Artillery and Army Hospital Corps Drafts, and some special service officers. The Dragoons and Mounted Infantry were despatched at once, horses, &c., being in readiness for the Mounted Infantry, and re-mount horses having been plentifully brought round from the Cape.
p225.
Heavy rain still continued, but the 17th passed very quietly, excepting that troops were rapidly pushed on, to be handy in case of emergency; Barrow's Mounted Infantry reaching Mount Prospect on that date ; the 83rd being on their way up from Newcastle; and C Battery 1st Brigade E.A., three troops 6th Inniskilling Dragoons, and four companies and drafts of the 97th arriving at Newcastle.