An element of the history of the PSA

Key points

• The first mention of the problem-solution approach of the EPO is (likely) the article of D.L.T. Cadman in CIPA journal, April 1983, p.274-281 (p.279). The relevant paragraph is cited below. 
• Cadman was the first chair of the "Chemistry Board of Appeal" (when the EPO had two Boards of Appeal). He most likely was a Principal Examiner of the British Patent Office before (there's a WIPO document listing him as such in 1972, AB/III/Inf/3). 
• Comparing the PSA to the chapter on inventive step in the 1978 first edition of the Guidelines, it was quite an innovation. I'm not entirely sure what the tests for inventive step of the German and British courts were at the time, though. 
• Note that the PSA then was slightly different, namely whether the effect was surprising. Nowadays, the question is more whether the feature was an obvious solution to the problem (or task) of obtaining the effect.

Courtesy CIPA - https://www.cipa.org.uk/