The thread on frame size is very topical for me, having just gone through the exercise of trying to get my fit right on the previously mentioned Peugeot "Course" that I have just bought.
I have some comprehensive measurements of a number of previous bikes that I have owned, and one in particular (an early 1990s Peugeot, mid/low in the range at the time) has very similar frame dimensions: seat-tube (53cm c-c), top-tube (54cm), down-tube, chain-stays are virtually identical to within a few mm. However the "Course" has a much shorter stem (60mm vs 105mm - length not height), and a shorter seat-post which is only just long enough for me (I'm 174cm/about 5'8", "normalish" proportions) I think that I will have to change the stem - it is a bit too short for me.
Another 1970s bike (coincidentally another Peugeot) that I once owned also had a short stem (60mm), in that case on a 58cm c-c frame.
Presumably as people have tended towards using smaller frames the stems and seatposts have got longer to get the overall fit correct...?