It was not always easy to know who had been a hero of the Resistance, who a died-in-the-wool collaborationist

From Trying to Please by John Julius Norwich.  Page 90.  

In those very early days, entertaining constituted something of a problem: it was not always easy to know who had been a hero of the Resistance, who a died-in-the-wool collaborationist. More than once a lunch or dinner guest would glance round the room on his arrival and murmur to my mother that he was sorry but he could not possibly sit at the same table as Monsieur so-and-so, whose shady dealings with the Germans were common knowledge. Eventually my parents resorted to submitting every guest list to their friend Gaston Palewski, at the time chef de cabinet to General de Gaulle; with his help they succeeded in filtering out most of the undesirables, though even then there were the occasional embarrassments.