Question: When was the library, at which John Metcalfe was the principal librarian in 1950, established ?

Context paragraphs:
Ernest Albert Savage: Ernest Albert Savage (1877–1966) was Principal Librarian of Edinburgh Public Libraries from 1922 to 1942, President of the Scottish Library Association from 1929 to 1931, and President of the Library Association (now CILIP) in 1936.  He wrote extensively on libraries and library science.  Savage had a career-long concern with the training and professional status of librarians.

John Winter Jones: John Winter Jones (16 June 1805 – 7 September 1881) was an English librarian.  He was Principal Librarian of the British Museum between 1866–73.  He was the first President of the Library Association in the U.K.

Henry Charles Lennox Anderson: Henry Charles Lennox (H.C.L.) Anderson (10 May 1853 – 17 March 1924) was instrumental in the establishment of the Mitchell Library (now The State Library of New South Wales) and held the position of Principal Librarian of the New South Wales Free Public Library as it was then known, from 1893 - 1906.

Frank Francis: Sir Frank Chalton Francis KCB (5 October 1901 – 15 September 1988) was an English academic librarian and curator.  Almost all his working life was at the British Museum, first as an assistant keeper in the department of printed books, and later as secretary of the museum, keeper of printed books and, between 1959 and 1968, director and principal librarian of the museum.

Charles Morton (librarian): Charles Morton MD (1716–1799) was an English medical doctor and librarian who became the principal librarian of the British Museum.

William Herbert Ifould: William Herbert Ifould OBE (28 August 1877 – 6 April 1969) was an Australian librarian and floriculturalist who was instrumental in the development of library services in New South Wales.  He was the Principal Librarian at the Public Library of New South Wales (now State Library of New South Wales) from 1912 until his retirement in 1942.

Library of Antioch: The Royal Library of Antioch was commissioned by Antiochus III (or Antiochus the Great) of the Seleucid Empire (a successor state of Alexander the Great's empire) around 221 B.C. in Ancient Syria and opened it to scholars.  Euphorion of Chalcis, an intellectually influential ancient poet from Greece accepted the challenge issued by the king and established the royal library at Antioch.  He also served as principal librarian until his death.  The library, along with the city itself, was considered by some to be the cultural capital of the ancient world, even more prestigious than Pergamon.

John Metcalfe (librarian): John Metcalfe (16 May 1901 – 7 February 1982) was an Australian librarian, educator and author.  He was the Principal Librarian at the Public Library of New South Wales (now State Library of New South Wales) from 1942 until 1958 and University Librarian at the University of New South Wales from 1959–1966.  He was involved in the establishment and development of the Australian Institute of Librarians (AIL), the Free Library Movement and education for librarianship in Australia.

State Library of New South Wales: The State Library of New South Wales is a large reference and research library open to the public.  It is the oldest library in Australia, being the first established in New South Wales (now a state of Australia) in 1826.  The library is located on the corner of Macquarie Street, Sydney and Shakespeare Place, adjacent to the Domain and the Royal Botanic Gardens.  The library is a member of the National and State Libraries Australasia (NSLA) consortium.

Henry Ellis (librarian): Sir Henry Ellis (29 November 177715 January 1869) was an English librarian and antiquarian, for a long period principal librarian at the British Museum.

Supporting paragraphs: John Metcalfe (librarian) State Library of New South Wales
Answer: 1826