FindMyPast indexes have:
Stephen Gallear, b 1878 , Parkgate, Rotherham for the 1896 Attestation.
Stephen Callear b 1881, Parkgate, Yorkshire for the 1914 Service record.
As I said, the WW1 record is available on Ancestry and mentions earlier service.
I have tried searching Boer War records on FindMyPast but no success. However, that is likely.