There's more - but slight frustration again! I've been looking at the earlier service with the Royal Sussex Volunteers. There is his service record covering the years 1898 and 1899 only in the 3rd Battalion. Although they were a part time unit, many volunteered to go to the Boer War with the regular 1st Battalion Royal Sussex and his presence in Chichester would indicate that he had rejoined the militia and was preparing to go to South Africa. His name appears in the Sussex Express of 3 May 1901 on a list of 3 officers and 99 men , including men from 1st and 2nd Militia Battalions, who left for South Africa on 3 May 1901. The newspaper says they were supposed to have left "several weeks ago" which would explain why he was in Chichester on 31 March that year.
Slight frustration because I find no record for that later service BUT he is listed in the Boer War medal list for the Sussex and, what is more, he then joined the Orange River Scouts, a South African regiment and I find him in their nominal roll.
Got to go shopping!
More in due course.
MaxD