Table:
text: Half marathon
Men
Men
Time_ Name_ Nationality Date_ Event_Place Source_
67:01 Brian Hill-Cottingham United Kingdom April 9, 1960 Romford ARRS
65:44 Ron Hill United Kingdom June 19, 1965 Freckleton IAAF, ARRS
65:42 Pete Ravald United Kingdom June 18, 1966 Freckleton IAAF, ARRS
64:28 a + Abebe Bikila Ethiopia October 21, 1964 Tokyo IAAF
63:22 a + Derek Clayton Australia December 3, 1967 Fukuoka Marathon IAAF
64:45 Ron Hill United Kingdom June 21, 1969 Freckleton IAAF, ARRS
63:53 Derek Graham United Kingdom May 2, 1970 Belfast IAAF, ARRS
63:46 Juan Rafael Angel Perez Costa Rica February 8, 1976 Coamo IAAF, ARRS
63:46 Jose Reveyn Belgium March 27, 1976 The Hague IAAF

Question: What was Derek Graham's half marathon time?