@Fire, Could it be Centaurea? My wild flower mix also includes (inter alia) oregano, cornflower, vipers bugloss, phacelia. Any of these ring a bell, I haven't a clue what they look like though although I can identify some of the other mix.
You beat me to it, @B3. I was going to say it looks like plantain to me, too. I've been reading up on health benefits of common weeds and was looking recently at some pics of plantain.
Very fuzzy, hairy leaves. I know what it is too, I just can't place it. I planted a load of wild flower seeds last autumn and quite a few blow in from neighbouring gardens.
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.