BBC1 drama Case Histories is to return next year in a new feature-length format.

The two new films, based on the novels of Kate Atkinson, will be made by indie Ruby Films and have been commissioned by BBC1 controller Danny Cohen.

Jason Isaacs will reprise his role of police inspector turned private investigator Jackson Brodie.

Case Histories first aired as a 6 x 60-minute series in June, delivering an average audience of 5.3m viewers (18.6% share) across the run.

The three two-part stories were on the first three of Atkinson’s four novels: Case Histories (2004); One Good Turn (2006); and When Will there Be Good News? (2008).

The first of the two new films will be based on Atkinson’s fourth Jackson Brodie novel, Started Early, Took My Dog, which was published last year.

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It will be adapted by Peter Harness.

Ruby is working with Atkinson on stories for the second 90-minute film and both will be shot in Edinburgh next spring.

Life on Mars writer Ashley Pharaoh, who adapted the first two books, is unavailable for writing duties on the second tranche because of “other commitments” according to the BBC.

Harness wrote episode five and six of the first series.

BBC executive producer Matthew Read said: “It’s incredibly exciting to have Jasson Issacs back as the complex and compulsive Jackson Brodie.

“The next series will continue to reflect modern Edinburgh on screen and turn what audiences love most about Kate Atkinson’s novels into feature length crime stories that shine a light on dysfunctional families.”