Thanks Stuart, and all for those interesting comments, the chinstrap is so obvious now!
Looking at the shoulder title image - my first impression was "SWB". I took a copy, rotated it, applied various filters and to me the central letter really looks like a 'W'. You will have to save this image to your pc and zoom in.
The medal ribbon on the Major could be a 1897 Jubilee - thin blue, white, blue, thin blue - it looks white/blue?/white. The ribbon on the Colonel (?) in the centre is certainly similar - pale/mid (not dark)/pale.
The 3rd bn SWB served in the west central cape from Feb 1900. Their Colonel - Charles Healey was awarded an 1897 Jubilee. I cannot find any pictures of him.
The problem comes in that I cannot find any other officer of the battalion with a Jubilee medal of any description. As to VDs, not sure where to check.
Happy to be accused of wishful thinking on the regimental title, and I realise there I cannot find two officers with Jubilee medals (allowing for issues with Ancestry's index).
Also - would a militia battalion have such young (looking) officers?
Researcher. Owner: The Register of the Anglo-Boer War 1899-1902. Interests: 24th Foot/South Wales Borderers/RRW/RW. South Africa generally. War memorials