"Metonymy is a figure of speech whereby one replaces a term by another whose meaning or reference is in a relationship of contiguity to it rather than in one of identity or similarity... This relationship may be causal, as with 'ear' for 'attention' ("Romans, lend me your ears"), or one of part-for-a-whole (the figure of speech known as synecdoche), as with 'Moscow' for 'Russia' - in fact any kind of close spatial or conceptual association. This tends to be conventionalized, but the type of relationship (e.g. of name of a place for an important institution or place associated with that place) can be transferred to quite novel acts of metonymic reference, as in "The pork chop left without paying" in a restaurant setting.
The metonymic relationship between The White House and the president of the United States... is a particularly clear-cut case"
--- Semantix / Michael Fortescue
This is like how "Downing Street" can refer to the Prime Minister of the United Kingdom, and when I say "London said" I don't literally mean that the city physically spoke with one voice.