In the UK, TV prequels are rare, or tend to be for limited runs only. For instance, in recent years, we’ve seen origin stories connected to Only Fools And Horses (Rock And Chips) and Keeping Up Appearances (Young Hyacinth), but the former only had three episodes, while the latter was a one-off. Prime Suspect 1973, a prequel to the classic Helen Mirren series, lasted for just one, six-episode series.