Provocation / Luc Thiet Thuan

hello,
Im unsure exactly what was held by the Privy council in Luc Thiet Thuan (1996) and the court of appeal in the cases of Newell/Ahluwalia/Dryden/Thornton/Humphreys.

From what I understand Luc Thiet Thuan basically confirmed Camplin and Morhall and the distinction between those characteristics which bear on the gravity of the provocation and those which concern D's level of self-control. From what I can see though this is the same as in the Court of Appeal cases, although perhaps less explicit. However, in one textbook it says that Lord Goff (delivering the majority judgement in Luc) said that relied too heavily on Newell.(??)

Also, in the Storey/Lidbury textbook it says "In Luc a majority of the Privy Council disagreed with this line of cases and held that psychological characteristics were not relevant in the context of provocation - and should be left exclusively to DR." However, to me this seems plain confused. In Luc they were concerned about maintaining the distinction between DR and Provocation but not when the psychological characteristic is relevant to the gravity of the provocation. Isnt this completely in line with all those cases as well as Camplin???

Also, on http://sixthformlaw.info/02_cases/mod4/cases_34_vol_provocation.htm#Luc%20Thiet%20Thuan%20v%20R%20[1996]%20PC
it says "R v Newell (1980), R v Ahluwalia [1992], R v Dryden [1995] and R v Humphreys [1995] doubted." without any explanation that I can see.

thanks for any help