Which BBC serialisation used the song "Maids when young never wed an old man"
It might have been in the 1980s, and I think was some classic book. The story is about a girl servant who is made pregnant by the son of the house where she works.
I have just started reading Moll Flanders, and wondered if it was that, but no. In the play there was a sister (who needed money to emigrate with the rest of the family) and the heroine gave her the pay-off from her baby's father and then had to go as a wet-nurse.