Guardian is, IIRC, not the bastion of "radicalism" it used to be; in any case, this is no op-ed, but rather a dive into the official archives, so it really doesn't matter where the article comes from. Just read Thatcher's notes themselves.
Oh, I know perfectly well about the use of derivatives etc, but that's not the issue here; the problem arises when derivatives (and derivatives of derivatives of derivatives, which only a handful of people in the world can wrap their brains around) are in the hands of persons who don't care about the underlying economics but are into it just to make a quick buck; I think that's clear from my paragraphs two posts above...
Thanks for the pdf, I'll print it out