Edict of Nantes, [13th April 1598]. This decree by Henry IV of France served as a guarantee to the Protestant Huguenots that their rights to worship would be respected. It granted them full civil rights and established a special court, the Chambre de l’Édit, composed of both Protestants and Catholics, to deal with disputes arising from the edict. Protestant pastors were to be paid by the state and released from certain obligations; finally, the Protestants could keep the places they were still holding in August 1597 as strongholds, or places de sûreté, for eight years, the expenses of garrisoning them being met by the king. (source)
However, it was revoked by Louis XIV in 1685 with the result that large numbers of French protestants fled to England to escape persecution. Over twenty thousand (out of an estimated 200,000 who fled France) of these religious refugees settled in Spitalfields, London.
This weekend in London there are a number of events to celebrate the contribution made to British life (and the silk-spinners who worked in Spitalfields, in particular). More details are available from Time Out.
Further information about the Huguenots can be found on the Huguenot Society's website.