But, in the end, it wasn't Cooper's defence of Miliband that caught the ear — even though she took her leader's approach of robotically mouthing the same line over and over (in this case, "Ed Miliband is doing a good job"). Rather, it was her attack on Iain Duncan Smith's recent speech on immigration and worklessness. This wasn't an attack on the idea that British workers are losing out in the great, globalised labour market. This wasn't even an attack on the specific of IDS's welfare reforms. It was an attack on the coalition's immigration policy, which, Cooper suggested, isn't matching up to the hardline rhetoric. More should be done, she said, to curb illegal entrants. There should be more controls. This was, it soon became clear, quite something from a Labour politician: a broadside against IDS from the right. And the broadsides continued, from the same direction, when the questions moved onto asylum seekers, imprisonment, and the like.
This is certainly tricky terrain for Labour. There will, no doubt, be some scepticism about their recent direction on immigration, not least because Cooper declined to endorse the Tories' aspiration to reduce net migration to the "tens of thousands". But this struck me as the clearest example yet of the party trying to exploit the coalition's exposure on the right, and I expect we'll see much more of it in future. In the process, Cooper was firm, assured and combative. Exactly the sort of performance that may have her party wondering whether they already have a suitable replacement for Ed Miliband.