Over the last two centuries, the word ‘patent’ has come to have a precise and technical meaning: a grant of monopoly powers over the commercial exploitation of an invention for a limited period. This conceals its origin. William Blackstone, the jurist, writing in 1768, was still familiar with the broader understanding of the word, in which a patent for invention was but one type of royal ‘letters patent’:

Thus letters patent were simply the document by which special privileges were conferred. Grants for invention were a relatively late arrival on the administrative stage, and were regarded as just one more instrument of royal policy. This meant that they were recorded indiscriminately on the patent rolls, among grants of land, office, honours, and other perquisites in the royal gift.

ELIZABETHAN AND EARLIER PATENTING PRACTICE

There are records since the reign of Edward III of ‘letters of protection’, given by the English crown to named foreign craftsmen, mainly weavers, saltmakers and glassmakers, with the intention of encouraging them to settle in England and transmit their skills to native apprentices. These grants did not confer any exclusive privilege or monopoly.