There were two forms of threepence, the currency issue and a special piece (like this one) for the Maundy Thursday ceremonies. Before 1937, both had the same design featuring the crowned numeral 3 on the reverse and were only distinguished by the proof-like finish of the Maundy issues. Starting in 1937, currency issues (listed on this site in the circulating coins section) had a distinctive new design while Maundy coinage retains the same reverse design to this day.
The 1968 Maundy ceremony was at Westminster Abbey.
Laureate bust of Queen Elizabeth II facing right ("First Portrait" Mary Gillick); around, ELIZABETH · II · DEI · GRATIA · REGINA · F : D :.
Within an open oak wreath, the numeral 3 below a crown and dividing the date 1968.
Threepence 1822 (Maundy) 3,960 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1823 (Maundy) 2,640 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1824 (Maundy) 2,112 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1825 (Maundy) 3,432 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1826 (Maundy) 3,432 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1827 (Maundy) 3,168 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1828 (Maundy) 3,168 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1829 (Maundy) 3,168 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1830 (Maundy) 3,168 Portrait by Benedetto Pistrucci (Laureate head) GEORGIUS IIII D. G. BRITANNIAR. REX F. D.
Threepence 1937 (Maundy) 1,325 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1938 (Maundy) 1,275 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1939 (Maundy) 1,234 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1940 (Maundy) 1,277 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1941 (Maundy) 1,253 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1942 (Maundy) 1,231 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1943 (Maundy) 1,239 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1944 (Maundy) 1,259 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1945 (Maundy) 1,355 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1946 (Maundy) 1,365 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1947 (Maundy) 1,375 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1948 (Maundy) 1,385 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX F : D : IND : IMP.
Threepence 1949 (Maundy) 1,395 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX FIDEI DEF.
Threepence 1950 (Maundy) 1,405 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX FIDEI DEF.
Threepence 1951 (Maundy) 1,468 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX FIDEI DEF.
Threepence 1952 (Maundy) 1,012 King George VI by Thomas Humphrey Paget GEORGIVS VI D : G : BR : OMN : REX FIDEI DEF.