I opened the cupboard that I fling it all in, and while attempting to chuck one more tub in, the whole lot came tumbling out. And I haven't seen some of it before.
So I think the bought stuff has been quietly having it off with the takeaway containers (each takeaway a different size of course so they don't stack) and has produced baby clip-it containers that I certainly haven't bought.
That's got to be the explanation, right?