The above plaque is on the back wall of the fountain, just above the spout. It reads:

1885
DRINK AND THINK OF HIM WHO IS THE FOUNTAIN OF LIFE

WITH THE CONSENT OF THE LORDS OF THE MANOR
THIS DRINKING FOUNTAIN IS ERECTED BY
MR. WILLIAM WARD
TO MARK THE SITE OF A CELEBRATED SPRING
KNOWN AS WALTON WELL
ADJACENT TO THE ANCIENT FORDWAY INTO
PORT MEADOW CALLED WALTON FORD

William Ward was Mayor of Oxford in 1851 and 1861.