The absence of the honour ASSAYE from above the Elephant and the presence of the separate, special scroll for SOUTH AFRICA indicate that this is a piper’s plaid brooch from a Volunteer battalion. It was the practice until after 1908 for auxiliary, ‘volunteer’ units to be forbidden the wearing of honour titles earned by the regular battalions. There are other, probably later examples where the scroll for SOUTH AFRICA is smaller and directly replaces the ASSAYE scroll of the regulars. The crown on both versions is of Tudor type (aka King’s crown) indicating a date after 1901.
As well as the 1st, Regular battalion of the HLI, there were elements of the 3rd and 4th (Militia) battalions employed, as well as composite, so-called Service Companies comprising men from the Volunteer battalions who agreed formally (via a legal process) to forego their mandated home-defence limitation and serve overseas in South Africa. The memorial to the HLI Regiment as a whole can be seen here:
http://www.roll-of-honour.com/Lanark...owHLIBoer.html
Following the 2nd Boer war, those Volunteer Battalions that had provided men for the deployed Service Companies were awarded the discrete honour SOUTH AFRICA 1900-1902
The more simple, elephant brooch is also for a piper, but this time for the 74th Highlanders (later 2nd Battalion HLI). It is apparently extremely rare and of course pre-1881.