You may not see this unless you’re watching TV at the right time – it airs as part of the BBC’s preview trailers on BBC One HD while local (standard definition) news is broadcast.
Meanwhile readers who want to catch the prelude short, Vastra Investigates on the family TV set can do so from Thursday by pressing the Red Button on your digital remote control. Available on Freesat/Sky/Virgin Media/Freeview, the episode can be viewed in a cycle during the following windows:
Friday 21st, 9pm-6am
Sat 22nd, 6pm-6.30pm, 7.55pm-8.50pm, 10.05pm-1.25am