| Issue Date | Patent |
| 31/12/1920 | GB156286 |
| 30/12/1921 | GB173835 |
| 29/12/1922 | GB191124 |
| 31/12/1923 | GB209150 |
| 31/12/1924 | GB226854 |
| 31/12/1925 | GB229683 |
| 31/12/1926 | GB243675 |
| 30/12/1927 | GB283254 |
| 31/12/1928 | GB303540 |
| 31/12/1929 | GB323501 |
|
| Issue Date | Patent |
| 31/12/1930 | GB340526 |
| 31/12/1931 | GB363858 |
| 30/12/1932 | GB386005 |
| 29/12/1933 | GB404308 |
| 31/12/1934 | GB422341 |
| 31/12/1935 | GB440719 |
| 31/12/1936 | GB459047 |
| 31/12/1937 | GB477578 |
| 30/12/1938 | GB498287 |
| 29/12/1939 | GB516337 |
|
| Issue Date | Patent |
| 31/12/1940 | GB531238 |
| 31/12/1941 | GB542235 |
| 31/12/1942 | GB550248 |
| 31/12/1943 | GB558349 |
| 29/12/1944 | GB566450 |
| 31/12/1945 | GB574316 |
| 31/12/1946 | GB583834 |
| 31/12/1947 | GB596285 |
| 31/12/1948 | GB615062 |
| 30/12/1949 | GB633875 |
|
| Issue Date | Patent |
| 28/12/1950 | GB648180 |
| 27/12/1951 | GB663940 |
| 31/12/1952 | GB685360 |
| 30/12/1953 | GB701780 |
| 29/12/1954 | GB721190 |
| 30/12/1955 | GB742700 |
| 28/12/1956 | GB764680 |
| 23/12/1957 | GB788350 |
| 31/12/1958 | GB806870 |
| 31/12/1959 | GB826320 |
|