Eleanor is leaving hints that it will soon be a landmark birthday for her. Sarah just feigns ignorance, like she knows nothing.
As she tells Clare that Eleanor has never revealed her true age. So no one really is supposed to know how old she really is.
However Sarah does have a surprise birthday party lined up for her mother. She has secretly invited her aged friends and told them all to keep quiet about it.
Only after talking with Clare, Eleanor has a mistaken suspicion that her daughter might be carrying on with another man.
The first series finishes with another took genteel episode. There really is not much story to this. There is a nice cameo from Paul Brooke as the mistaken suitor for Sarah.