One thing that did strike me out as peculiar to the presentation, but which may not be reflected in the book, was the critique of the mainstream view of trade on the basis of Ricardo/Mill rather than the Heckscher-Ohlin (HO) model. Note that comparative advantage in the HO story is associated to full utilization of resources and relative prices determined by scarcity (for a critique see here). That's clearly not the case in Ricardo.
Also, the Ricardian (properly understood as part of the surplus approach) story is less about the benefits of trade in general, and more about which social class benefits and which one loses from protection (see my discussion here).
One last point about the talk, that I would have liked to discuss with Peter (I had to leave for a defense) was on Mill. He was a peculiar author in-between classical political economy and marginalism, and his contributions are more problematic to properly understand than authors like Ricardo and Marshall. In fact, Mill is a key author to understand the break between the surplus approach and marginalism. As noted by Krishna Bharadwaj, what was Ricardian in Mill's theories does not appear in Marshall's work, and what is proto-Marshallian in Mill's ideas was not part of Ricardo's views of political economy. In that sense, while I'm comfortable with a Smith/Ricardo approach to trade, I'm less keen about adding Stuart Mill to the mix.
PS: I should have noted that his discussion of trade policy builds on Hamilton, List, Prebisch, Myrdal, Singer and others, like the work of Ha Joon-Chang. A paper of mine on a similar subject is the entry on Export Promotion for the International Encyclopedia of the Social Sciences, edited by Sandy Darity (here).