You don't give any dates, which makes your query rather vague. I assume from the wording of your query that you do not live in South Africa, although you do not state this.

Nor do you say where or when William Henry Mellors died - if he died in South Africa there should be a Death Notice, an legal document which can have lots of good information if the person who completed it had the information to hand.

Are you sure that a South African birth certificate would include the date of birth of the father? I have never seen a full SA birth certificate so cannot tell you - my short birth certificate does not even contain parent's names.

An index to the South African Archives, or at least a large part of them, is online at the following address:

http://www.national.archives.gov.za/index.htm

I have had a look throught it for you - there are very few entries for the name Mellors (I also tried spelling Melors and Mellers) and only 4 for a William and which I list below:

DEPOT NAB
SOURCE CSO
TYPE LEER
VOLUME_NO 1405
SYSTEM 01
REFERENCE 1894/4307
PART 1
DESCRIPTION
DEPOSITION OF SERGEANT ALEX DONALD 3RD DRAGOON GUARDS APPLYING FOR A
WARRANT FOR APPREHENSION OF PRIVATE WILLIAM MELLORS 3RD DRAGOON
GUARDS AS A DESERTER.
STARTING 1894
ENDING 1894
REMARKS M1894/65.

***

DEPOT NAB
SOURCE CSO
TYPE LEER
VOLUME_NO 1405
SYSTEM 01
REFERENCE 1894/4307
PART 1
DESCRIPTION
DEPOSITION OF SERGEANT ALEX DONALD 3RD DRAGOON GUARDS APPLYING FOR A
WARRANT FOR APPREHENSION OF PRIVATE WILLIAM MELLORS 3RD DRAGOON
GUARDS AS A DESERTER.
STARTING 1894
ENDING 1894
REMARKS M1894/65.

***

DEPOT NAB
SOURCE MSCE
TYPE LEER
VOLUME_NO 0
SYSTEM 01
REFERENCE 2938/1918
PART 1
DESCRIPTION
MELLOR, WILLIAM.
STARTING 1918
ENDING 1921
REMARKS OR 3/8 713 VE 18/18.

***

DEPOT NAB
SOURCE MSCE
TYPE LEER
VOLUME_NO 0
SYSTEM 01
REFERENCE 9906/1924
PART 1
DESCRIPTION
MELLORS, WILLIAM CECIL. (UNMARRIED).
STARTING 1924
ENDING 1930

***

The latter two would appear to be Death Notices.

Good Luck,

Richard Ball