Here are some facts from AY history: http://www.finnairgroup.com/group/group_14_6.html

As long as I recall (since late 1970īs) there has not been first class service on Finnair flights, at least in three class configuration. The better one may have been called "First Class" initially, later "Executive Class", and "Business Class" nowadays. The lounges appeared to the smallish HEL airport by the time AY Plus was founded. Gold was the highest tier then and had its own lounge apart from Business class lounge. I do not remember if Silver card holders had lounge access those days. Before joining OW, Finnair used to have close co-operation with the QualiFlyer (Austrian, Sabena, Swissair, Crossair... etc.) and later with Lufthansa.