Assuming that whoever registered his death actually knew his birthdate,
then as his birth was the day before the end of Quarter3, it is fair to assume that the following Q4 registration is his . . . . .
Should you not have his full birth details/certificate then the certificate may be ordered using . . . . .
Birth 1901 QDec Henry William T Slaughter Bedwellty 11a 71
. . . . . giving his parents' details (and what "T" stands for").