The alleged libertarian wave in pre-Keynesian economics was refuted half a 
century ago by Lionel Robbins in "The Theory of Economic Policy in English 
Classical Political Economy". Viner's famous article on Smith's qualms about 
laissez-faire was published as early as 1927.

Economic historians have downplayed the influence of laissez-faire at least 
since Brebner's paper on the subject (Journal of Economic History, 1948). 
Ellen Frankel Paul summarized the debate in an article
available online: http://www.econlib.org/library/Essays/LtrLbrty/fplLNB.html

Carlos Rodriguez Braun