Can someone explain the job titles signified by Numbers in UK politics and defense? They're used as shorthand when I read the news and listen to the BBC but I never remember them accurately. There also seems to be an offhand use of addresses to refer to the PM staff and Parliament, yeah? Is there a cultural underlying that also explains 007 and MI6 etc?
Are you referring to Number 9, 10, 11? If so then it is simply the addresses in Downing Street representing the residences and offices of the Chief Whip, Prime Minister and Chancellor of the Exchequer, in that order. So in short hand they are used to describe either the people in those positions, or more commonly the group of civil servants and political staff surrounding those posts. Generally used during political coming and going amongst the government. Especially used to describe partisan in- fighting.
As for MI5 and 6 they represent the historic names for numerically titled departments of the old War Office and simply stand for Military Intelligence. I think there were up to about 18 at one point.
Is that what you mean?