British TV Movie About Nanny Seeing Ghosts

by Lior Bar

In the 90's, I saw a made for TV movie about a nanny that arrives at a mansion in the English countryside.

The nanny starts seeing the ghosts of a man and a woman. At one point, she sees the female ghost playing a piano.

In the end, the boy and the girl, whom the nanny was hired to take care off, are possessed by the ghosts. The movie was based on a book.

My question is: what is the name of this movie?