I've been reading Pakenham's "The Boer War" and so far he's mentioned that, owing to the new style of "unseen warfare" brought about by both sides using smokeless powder, British officers started to carry rifles, abandoning their swords and revolvers, specifically when Roberts began his march to Bloemfontein.
"True to the new style of warfare, the officers carried rifles instead of swords" - pg 312
Considering how the British Army is believed to have learned a lot from this war, why is it that during WWI the vast majority of their officers appear to have reverted to using revolvers? Especially since conflict with Germany was increasingly likely after 1900 and most of the Boers' rifles were Mausers, similar to what the British would fight against in 1914.
After all, both of the British C-in-Cs from the First World War, French and Haig, and a number of other significant officers all served in the Boer War, so why did they not continue to use these developments later on?
You see, it wasn't uncommon for officers to use sidearms such as revolvers during WW1. In fact, Austro-Hungarian, French and German officers rarely carried rifles. It was not "gentlemanly" as the whole concept of class still existed during the first world war.
Besides, hundreds of thousands of troops carried rifles with them, there wouldn't be much difference.