All Creatures Great and Small on Masterpiece

8 p.m. on . A fondly remembered TV adaptation from nearly 50 years ago of James Herriot’s stories about his life as a 1930s Yorkshire veterinarian gets a glowing new treatment in this seven-part series, starring newcomer Nicholas Ralph in his television debut as Herriot, with Samuel West as Herriot’s crusty mentor, Siegfried Farnon. Rachel Shenton stars as Helen Alderson, who becomes Herriot’s love interest. Callum Woodhouse (“The Durrells in Corfu”), Anna Madeley and Matthew Lewis costar; Diana Rigg also has a featured role.