Opera star Kiri Te Kanawa is to star in an episode of Downton Abbey, while veteran US star Shirley MacLaine is rejoining the cast.

The fourth season will see the New Zealand-born singer play a house guest and she will sing during her visit.

MacLaine is back playing Martha Levinson, the mother-in-law of Lord Robert Crawley, played by Hugh Bonneville.

Other new actors joining the cast include veteran actress Harriet Walter, and former EastEnders star and theatre actor Nigel Harmon.