Tom, Welcome to the Forum
Regarding your great-grandfather's brother - are you sitting comfortably?
Using the name search facility on this site (look to the top left of your screen) confirms you are correct about the place he died and adds the date of 25 February 1902.
This document confirms the date but unusually leaves out the place:
He appears in a transcript record on Find My Past which describes the action he was killed in as follows:
"On 24 February 1902 a convoy commanded by Lt-Col W.C. Anderson heading for Klerksdorp bivouacked on the farm Elandslaagte by the Yzer Spruit. Early the following morning it started and after a march of some three kilometres was attacked by a commando under the command of Asst Cmdt-Gen J.H. de la Rey. After very strong resistance, the convoy was forced to surrender. British losses were 187 killed and wounded whilst the Boers lost 51 killed and wounded."
The record also says he was awarded the King's South Africa Medal with the South Africa 1901 & South Africa 1902 clasps.
He is listed as a casualty in the papers of the day - this one, from the Lichfield Mercury 7 March 1902, gives the most detail and is somewhat confusing:
He should be findable on a Queen's and King's South Africa Medal Roll but I cannot find them, so afraid I cannot tell you what clasps his Queen's Medal was adorned with.
However he comes up on the following two medal rolls:
They mean he was part of the forces Kitchener led to sort out the Madhists and exact revenge for the death of General Gordon of Khartoum and he would have fought in the Battle of Omdurman (2 September 1898) and would have received two campaign medals - the Sudan Medal and the Khedive's Sudan Medal - the latter with a clasp bearing the word "Khartoum".
His attestation papers and service records are not extant which is usually the case for a soldier who died in service. However, Find a Grave tells us he was buried in Klerksdorp Old Municipal Cemetery.
Regards, David.