For example, skinners, or traders in pelts, were by a 14th Century royal decree unable to market their goods "unless on the security of six reputable men of that mistery".

BBC: Lessons from history: Can royalty guarantee a free press?

Around that time, the cutlers claimed that "foreigners" were largely to blame for poor quality merchandise: "When it is remembered that a 'foreigner' was not simply an alien but anyone, Londoner or otherwise, who was not free of the City - a freedom gained through membership of a mistery - the extent of their power to control the trade will be appreciated, " adds Girtin.

BBC: Lessons from history: Can royalty guarantee a free press?