Who invented the first envelope?

The first envelopes were made out of clay and were developed in ancient Babylonia in around 3500 B.C. Paper envelopes were first used in China over 2,000 years ago, but it was not until the 19th century that British manufacturers such as Warren De La Rue began producing modern envelopes.

Rowland Hill's prepaid letter sheet of 1840 is seen as one of the forerunners of the modern envelope. The sheets could be written upon and folded; then, the two ends were stuck together with an adhesive gum. In the same year, William Mulready produced illustrated letter sheets, but they proved to be unpopular with the public.