Diehard fans of Joan Plowright (or Natalia Ginzburg) may be interested in these posters offered by the National Theatre Archive. They're from the 1968-69 run of Ginzburg's play, The Advertisement, translated and adapted by Reed. The production was directed by Donald MacKechnie and Sir Laurence Olivier, and starred (besides Dame Joan) Suzanne Vassey, Louise Purnell, Edward Petherbridge, Anna Carteret, and Sir Derek Jacobi.
The National Theatre also has an extensive, searchable catalog of performances and items in their archives.