Julie Christie's odd expression

In the final scene, Laura has not yet comprehended what has happened to John, puplover. She doesn't look happy, she looks bemused and stunned. I think that Laura finds herself being pulled through the funeral procession without realizing what she is doing and is oddly smiling because she merely feels a connection to her husband, not his death. She might also be bizarrely convincing herself that her family is whole again because she believes that her daughter has never left her life, and John becomes a special focus at the same time.

In fact, John is a person called paredros, created by the goddesses in Greek mythology just to help themselves. Although John has the 6th sense, he lives according to the strict positivist worldview. In the movie (and in the book), 3 different motifs of the mother goddess are actually shown. Their deceased daughter, Julia, and twin sisters. Maybe these 3 figures symbolize a single female god. Thinking about the expression on Julia's face after John's death; in other words, it is possible to see it as the re-emergence of the god who took his revenge. We also see that there are posters with feminist content in some scenes of the movie. I'm looking at it from a purely mythological perspective.

Nic Roeg has discussed this. She is smiling because John and Christine are ‘reunited’.