Apologies for my late arrival on the scene ....
Hopefully I can offer answers to some of smoke's questions ....
Use of khaki field uniforms by the British originated with the Indian Army (maintained as a separate entity after Britain took over direct administration of India from the Honourable East India Company following the 1857 Mutiny.) As you likely know, the very word "khaki" is derived from a Hindustani (Urdu) word meaning "soil coloured" or "dust coloured", from a Persian word for "soil/dust". British Army regiments stationed in India were quick to adopt it as practical campaign clothing for hot/tropical areas, and its use spread ... particularly for service in Africa - such as the conflicts in Egypt and the Sudan in the 1880s and 1890s.
The first standard pattern khaki uniform for the British Army (i.e. a formally adopted pattern for universal issue ... at least where khaki was deemed appropriate) was the Pattern 1896 khaki drill (KD) tunic and trousers.
Note: "drill" in this case does not refer to "drilling" activity, but to a type of fabric - i.e. "a stout durable cotton fabric with strong bias (diagonal) in the weave".
Canada's first troop contingent to South Africa was a specially-raised volunteer unit designated as the 2nd (Special Service) Battalion, Royal Canadian Regiment of Infantry, consisting of eight 125-man companies. The war broke out on October 11th, 1899, and recruiting for this Battalion (primarily within the ranks of the existing Permanent and Active Militia, of course) began on October 14th. The unit was rapidly filled, equipped and embarked for South Africa, arriving on November 29th .... seemingly a lot quicker than things might go in today's world, considerring that they were month at sea!
They were kitted out in cotton khaki service uniforms produced in Canada but, since proper khaki drill cloth was not available, they were actually made of a canvas-like material dyed to a khaki colour. They proved to be stiff and uncomfortable (i.e. chafing) compared to proper khaki drill, and soon bleached out to near-white in the harsh summer sun of South Africa, and were soon replaced with uniforms made of proper khaki drill.
Men of the first contingent immediately following their landing in South Africa:
Note that, instead of the British Pattern 1888 Slade-Wallace Equipment, their leather equipment is the uniquely Canadian Pattern 1899 Oliver Equipment, most easily distinguishable by the single large, centrally-located ammunition pouch.
Of course, October-March is the summer in South Africa, so cotton drill uniforms were ideal, and the practicality of drab uniforms for modern warfare, particularly against more sophisticated enemies armed with accurate rifles, had become obvious by this time. However, it also became evident that cotton clothing would be unsuitable for campaigning in cooler and/or wetter conditions such as would soon occur in the South African winter. Accordingly, the first standard pattern of khaki serge (i.e. wool) uniform was adopted by the British: the Pattern 1899 jacket and trousers. Unlike the P'96 KD tunic (which had flap-covered breast pockets, but no lower pockets), the P'99 serge tunic for some reason had flap-covered skirt pockets, but no breast pockets! Considering that infantry equipments of the day consisted primarily of largish pouches on waistbelts (undoubtedly why the P'96 tunic had breast pockets but no skirt pockets) the lack of breast pockets on the serge tunic soon became a source of annoyance for British troops, and a number of examples (and photographs) exist of such tunics modified by the addition of breast pockets. The Pattern 1902 tunic you refer to had breast pockets, of course.
That said, there seem to be a lot of "variants" (in terms of exact cut, colour, etc.) of such uniforms. Rather than get into all that here, check out this thread on the Victorian Wars Forum, which started as a presentation by one of the collector-members of examples of British Officer's khaki dress in the 1896-1902 period, but then developed into a discussion of khaki drill and serge uniforms, generally -
http://www.victorianwars.com/viewtopic.php?f=19&t=6669&start=15Interestingly, there seems to be considerable evidence that Canada may have been first to adopt a pattern of khaki wool serge tunic with both breast and skirt pockets, worn (perhaps trialled?) during the Boer War. Various photographs exist of Canadian Boer War soldiers wearing such a tunic, evidently pre-dating adoption of both the P'1902 uniform by the British and the somewhat different Canadian Pattern 1903 khaki serge uniform. Here is a thread started by me on the Victorian Wars Forum discussing this, with plenty of photos -
http://www.victorianwars.com/viewtopic.php?f=19&t=7768&start=15Here is just one of the photos from that thread, showing a member of one of the Mounted Rifles units Canada subsequently sent .... at the specific request of the British, who had learned that foot infantry were at a distinct disadvantage in this campaign -
.... and a photograph of a 2nd Canadian Mounted Rifles patrol in South Africa, wearing serge uniforms. (Although it is not really possible to ascertain if it is the same uniform as shown above, the tunics clearly do have breast pockets, which the British P'1899 serge uniform lacked.) -
I have to go do some "grandparenting" .... Hopefully I can address some of the other issues raised in this thread, later ....