I have attached an envelope I have that Albert Edward Harcourt sent home to Leicester in May 1900! I thought you might want to see it.
To start with, LinneyL was correct in saying that his correct number was '22566', as can be seen by this envelope which proves that, and also proves the unit he was with 2 Company Western Division RGA. He is listed as a 'Gunner' as mentioned, however, he actually referred to himself as a Bombardier!! as can be seen by this envelope, he, starts off at the top "From Br. (Bombardier) A.E. Harcourt...".
Now I actually have the info on how he tragically died! And to help with that two maps, one a close up to help make sense of where he actually died!
Lancaster Hill, Vryheid - “At South Gun Post, 'one of the warmest corners' of the battle, the troops under Captain Mangles and Lieutenant Drought defended their excellent fortifications 'with marked bravery'. The garrison was awakened by the musketry on Mounted Infantry Plateau and immediately manned the defences. At about 02:45, Boer voices were heard below the 12-pounder gun emplacement. Battle was joined at some point between 02:45 and 03:30, with the gun's muzzle depressed to its utmost - and the trail raised - to sweep the steep hillside to the left front of the position, at a range of some 300 metres. The Boers, led by Assistent-veldkornet Piet Henderson, had crept to within 50 metres before being forced to retire. Following this flurry, the Boers settled down to a steady fire, gradually encircling the position from dawn onwards. The British response was aimed at halting the assaults at a safe range - 600 and 1500 metres. The Boer fire slackened toward midday, followed by a renewed onslaught, mainly on the right flank, between 17:00 and sunset. The Boer numbers are uncertain, as was the case with the other positions assaulted, but Captain Mangles reported counting 60-70 Boers when the attackers withdrew in the evening. Only one casualty is specifically identified at South Gun Post. He was Gunner A E Harcourt, who served as a gunlayer on the position's artillery piece. He continued serving the weapon even after the Boer rifle fire encroached to within 300 metres, until he was mortally wounded in the face. His courage was rewarded with a commendation from Major Carleton.” - 11th December 1900.
Back to the envelope, this was posted at or near Darnall (Natal) in May, possibly mid May, and arrived in Leicester on the 3rd June 1900. Hopefully the address on the envelope will help you track down more info.