What is considered "centrist" in other countries is stereotypically considered "left-wing" in the USA.
Let's write "commie" instead then, so readers would know in what context to read it...
Anyway, this wikipedia does not exist for the exclusive benefit of an American audience. And the LibDems do occupy (traditionally at least) the centrist niche in the British political spectrum (with Labour to their left, and the Conservatives to their right).
--Herman (who thinks 'left-wing', 'centrist' and 'right-wing' are rather meaningless indicators anyway)