Our Royal Charter was granted in 1940, which gave us independent permanent status for the first time.  

The Charter begins:

THE BRITISH COUNCIL

Charter of Incorporation

Granted by

His Majesty King George VI

1940

Whereas it has been represented to Us by Our Principal Secretary of State for Foreign Affairs that for the purpose of promoting a wider knowledge of Our United Kingdom of Great Britain and Northern Ireland and the English language abroad and developing closer cultural relations between Our United Kingdom of Great Britain and Northern Ireland and other countries for the purpose of benefiting the British Commonwealth of Nations and with a view to facilitating the holding of, and dealing with, any money provided by Parliament and any other property, real or personal, otherwise available for those objects and with a view to encouraging the making of gifts and bequests in aid of the said objects, it is expedient that the voluntary association now existing and known as the British Council should be created a Body Corporate.

The charter also gave us the right to our own coat of arms, and this was granted in 1941.

The original charter was amended by a Supplemental Charter in 1993.