Dame Helen Mirren has won three Baftas for her role in Prime Suspect

According to early figures, the show, which stars Dame Helen Mirren, won 33% of Sunday night television viewers.

It was the first part of the final outing for Detective Superintendent Jane Tennison, who has been solving murders on-screen since 1991.

The concluding episode of Jane Eyre secured 6.7m viewers - the biggest audience of its four-week run.

The series was written by Sandy Welch, who adapted the Bafta-winning version of Charles Dickens' Our Mutual Friend.

Ratings battle

On Saturday, 6.7m viewers tuned into the second episode of BBC One's high-profile drama series Robin Hood - down 1.5m from last week's opener.

Audiences for Strictly Come Dancing also fell, but ITV's X Factor gained a million viewers for the first live final of the series.

The weekend's provisional ratings will come as a relief to ITV, which suffered from poor viewing figures in the summer.

Series such as Love Island and It's Now Or Never fared badly with audiences, while the channel faced rising competition from digital TV stations.

The concluding episode of Prime Suspect will be shown on Sunday.