:::The point is, that you are claiming that it is regularly used in British English as emphasis. This is just not true. Ask the man on the Clapham omnibus what the word 'period' means and I very much doubt he is going to say it means emphasis or a full stop unless he qualifies it as an Americanism. The supposed emphasis comes from its use in American English where its vocalisation  means "full stop, end of discussion". Its use in modern Britain is solely based upon its usage in American English and the seepage that is all too common from American TV and films.