I've just noticed this in the schedules. I don't know what it will be like, but it might be worth a look. It's labelled as a series, but I can only see a single episode in the schedule.
DOCUMENTARY: Scotland's Scenic Railways
On: Channel 4 (4)
Date: Sunday 15th December 2019 (starting in 6 minutes)
Time: 19:00 to 20:00 (1 hour long)
An anytime alert is set for 15 minutes before the programme starts
Beneath vast mountains and across open moorlands, Scotland's railways connect coastal towns and rural villages through a Highland landscape voted the world's most beautiful railway. This programme meets the people who work on the railway and the steam enthusiasts who safeguard these iconic routes, offering a glimpse into a diverse community united by a passion for the nation's railways.
(New Series, Audio Described, Subtitles)