The ninth episode of The Changes airs on BBC1, adapting the novels of Peter Dickinson into a ten-part television serial starring Vicky Williams and Keith Ashton. Tom Chadbon (Doctor Who, Blake’s 7) and Oscar Quitak (Brazil) guest star. The series was filmed in 1973, but has been held for broadcast until 1975. 
Nicky and Jonathon venture out to the mountains where Michael and Mary claim they’ve seen extraordinary storms brewing. They discover what seems to be an abandoned rock quarry, until they discover a disheveled man inside a large cavern. They greet him and listen to his rants about a “power”, later finding a journal describing an ancient power awakened, and a mention of Merlin. Though Jonathon is skeptical, Nicky is certain that they’re close to the source of what has changed the world, and the two set out to reverse that change.
written by Anna Home
based on the novels by Peter Dickinson
directed by John Prowse
music by Paddy Kingsland
Cast: Vicky Williams (Nicky), Keith Ashton (Jonathon), Tom Chadbon (Michael), Merelina Kendall (Mary), Oscar Quitak (Mr. Furbelow)
Notes: April 19th is pinned down as the date the madness began. It’s also refreshing to see an episode of a BBC genre series admit, right up front, that it’s filmed in a quarry.
LogBook entry by Earl Green