what british series did kelly reilly play a teen in one episode

The British series you’re probably thinking of is Prime Suspect. Kelly Reilly’s first screen role was in that ITV police drama, where she played a 16-year-old drug-addicted schoolgirl framed for murder by her mother.

If you meant a different one-episode teenage role, tell me anything else you remember — like the plot, era, or whether it was a crime drama or period piece.