Yes Steve, it is a memorial rather than graves and tombstones.
The following men have "age unknown", but I have been able to find what appears to be their birth year, according to the 1911 Census, when the 1st Battalion was in the district of Medway (at Chatham), and the 2nd Battalion was in the "County" of "Overseas Military" (at Pretoria)
Service No Birth Name
4622 1878 MORRIS, FREDERICK, F
6212 1882 SYKES, ALFRED JOHN, A J
6228 1878 SMITH, ERNEST WILLIAM, E W
6269 1889 HANDS, JOHN, J
6513 1881 HOOPER, EDGAR CHARLES, E C
6833 1879 MORTIN, ERNEST, E
7080 1888 GARDNER, JOHN, J
7813 1891 ROGERS, EDWARD, E
7827 1889 DYKES, THOMAS, T
7885 1878 ALLEN, THOMAS WILLIAM, T W
7924 1886 PRICE, WILLIAM ARTHUR, W A
8061 1886 INSKIP, ROBERT, R
8196 1892 O'CONNOR, THOMAS, T
8234 1884 JORDAN, GEORGE OSCAR, G O
8292 1872 LYNCH, HUGH, H
8463 1890 ROGERS, FREDERICK, F
8553 1886 LEWIS, EDWARD JOHN, E J
8669 1889 COLE, HARRY, H
8718 1888 NICHOLLS, FREDERICK, F
8740 1885 HOWCROFT, HENRY, H
9019 1884 WESTON, HERBERT, H
9124 1883 PACKHAM, CHARLES ALFRED, C A
9255 1886 MOSS, CHARLES HENRY, C H
9390 1889 SCOTT, WALTER WILLIAM, W W
9485 1889 YEND, JAMES, J
9668 1886 GOLDSMITH, GEORGE, G
9857 1889 MAYERSBETH, ROBERT, R
10046 1872 KYLE, ALEXANDER WILLIAM, A W