P2 is the common name for the Italian masonic lodge, Propaganda Due.
It became the target of considerable attention in the wake of the collapse of Banco Ambrosiano (one of Milan's principal banks) and the 1982 murder of its president Roberto Calvi, quite certainly killed in London (despite a dissimulated suicide).
Calvi's connections with the Grand Master Licio Gelli became a particular focus of press and police attention, and caused the lodge (then secret) to be discovered. A list of adherents was found in Gelli's house in Arezzo, containing a thousand of names among which very important state officers, a few politicians and a number of military officers, many of them enrolled in the Italian secret services. Notably, the current Italian prime minister On. Silvio Berlusconi was in the list, but at the time he was not already in politics. Another famous member was Victor Emmanuel, Prince of Naples, current head of the House of Savoy.
A delay in the publication of the list caused the prime minister of the time, on. Arnaldo Forlani, to be generally suspected and he effectively soon resigned.
The lodge was then examined by a special commission of the Italian Parliament, which works were directed by on. Tina Anselmi (Democrazia Cristiana). The essential results of the inquiries were that it effectively was a secret association, even if no proof was found of specific crimes committed. The lodge was then forced to solve, as a a secret association, quite generally considered as potentially capable to organize and put into effect a golpe. International relationships, mainly with Argentina (Gelli repeatedly suggested he was a close friend of Juan Peron) and with some people suspected of belonging to American CIA were also partly confirmed; but soon a political debate overtook the legal level of the analysis.
Masonic institutions have always been totally tolerated and respected in Italy, but a special law was issued that prohibited secret lodges; official Grande Oriente d'Italia kept very distant from Gelli's lodge and only claimed for the obvious respect for honest freemasons. Other laws introduced the prohibition for some categories of state officers (and military officers, especially) to adhere to such clubs.