In England a provisional patent lasted for three years , a full patent for 16 . I am not sure whether this was from date of first grant or after the full British patent had been granted .
Any patent is only valid in the country of origin unless reciprocal agreements have ben reached with other countries
Many provisional patents were taken out and products advertised as " patented" that actually were not protected .
Needham ejector work although it should be noted as one of the first successful ejectors was fortunately quickly superseded as it was not reliable in general and comparatively weak in operation . Greener abandoned it not for reasons often repeated that so many craftsmen had been killed in the Great War , but simply as a better system the Baker was used enabling shallower bodies and was less costly to produce .
