Image caption Beleaguered police officer Catherine Cawood is at the heart of Happy Valley

Hard-hitting drama Happy Valley is coming back for a second series, the BBC has announced.

The next series will let viewers "delve deeper" into the world of Sarah Lancashire's character Catherine Cawood, according to producers.

The first six parts hinged on a kidnap plot in the small West Yorkshire town where Catherine is a police sergeant.

Work on the second series is due to begin in 2015 and will be broadcast later in the year.

Happy Valley, which was created by Bafta-winning screenwriter Sally Wainwright, proved a ratings success with a weekly audience of eight million viewers and has been considered one of the strongest dramas of the year so far.

BBC One controller Charlotte Moore called the show's initial run "visceral, emotional and provocative from beginning to end", referring to a cliffhanger ending as the action drew to a close.

"It was fantastic to see our audience on tenterhooks, begging for more. I can't wait for the second series to begin," she added.

Wainwright's other credits include two series of Last Tango In Halifax, which won best drama series at last year's Bafta Awards and additional writing accolades.

It also starred Lancashire, who was nominated for a Bafta and is considered a strong bet to make the shortlist for her performance in Happy Valley at next year's ceremony.

Wainwright told the Radio Times earlier this year that plans were afoot for a second series.

The serial was mentioned by BBC head of television Danny Cohen as a homegrown drama which is more than a match for US imports.