This was Ed Miliband's instruction to Labour MPs and activists: to refer to the government not as "the Coalition" but as the "Tory-led" Government. The term has been applied consistently by Labour bods ever since.
Okay, if (as usual) the left wish to tweak the language to further their narrative, then I think a little 'sauce for the gander' is in order. How about the rest of referring to Labour as the "Trade Union-controlled opposition" from now on? It's at least as accurate!