he was commissioned into the RE and served in the Boer War as adjutant in the 1st Railway Pioneer Regiment. He was awarded the DSO for his Boer War service.
At the start of the Great War he was appointed as the official war correspondent on the Western Front. He was inspired by the idea for the tank having see the British soldiers advance towards the German machine guns with no protection whatsoever. His suggestion was initially dismissed by French but taken up by Churchill who established the Landship Committee, which led to the development of the tank.
Dr Arnold van Dyk of Bloemfontein, bought all (or most) of ED Swinton's personal diary & papers. They are most impressive. Possibly the ones that you are referring to. Dr van Dyk has a HUGE collection of Boer memorabilia, he is also an absolute mine of information of the ABW.