History records the existence of a sign language within deaf communities in England as far back as 1570. British Sign Language has evolved, as all languages do, from these origins by modification, invention and importation. Thomas Braidwood, an Edinburgh teacher, founded 'Braidwood's Academy for the Deaf and Dumb' in 1760 which is recognised as the first school for the deaf in Britain. His pupils were the sons of the well-to-do. His early use of a form of sign language, "the combined system", was the first codification of what was to become British Sign Language. Joseph Watson was trained as a teacher of the deaf under Thomas Braidwood and he eventually left in 1792 to become the headmaster of the first public school for the deaf in Britain, the Asylum for the Deaf and Dumb in Bermondsey.