It doesn't look as though it's the same Arthur John Charles Hunnikin
Service Records
Arthur John Charles Hunnikin - No: 24045 Imperial Yeomanry
Born: Brentford, Essex
Occ: Carman
Enlisted: 30 Jan 1901
Killed at Tweefontein 25 Dec 1901Total Service towards Engagement to 25.12.1901 - Death - 330 days
Home: 30.1.1901 - 7.3.1901 - 47 days
South Africa: 8.3.1901 - 25.12.1901 - 330 days
Next of Kin: Father - Arthur Hannackin, Wypickam Villa, (cant' read next line), Chelmsford, Essex
Not Married
Just did a google search for Arthur John Charles Hunnikin and found this
https://angloboerwar.com/34th Company, 11th Battalion
The 34th (Middlesex) Company was raised in 1900.
Surname Forename No Rank Notes
Hunnikin Arthur John Charles 24045 Private Source: QSA Medal Rolls