I've had a couple of enquiries about the Emmerdale Farm novels. These were published from 1977-1989, and written first by Lee Mackenzie and then by James Ferguson. The first novel was called The Legacy, and the last Wives And Lovers.
Additions to the series were usually advertised on ITV directly after an episode of Emmerdale Farm: "The latest Emmerdale Farm novel, Wives And Lovers [and so on], is now available." The screen capture above is from 1989.