Unofficial overnight figures show that Broadchurch was the most popular programme between 9pm and 10pm, with a 36.4% share, or 8.7 million, of the total TV audience. When excluding ITV +1, 8.4 million people tuned in; a 35.3% share.
The final series of Broadchurch was the most-watched of show's three. The crime drama, which stars Tennant and Olivia Colman as murder detectives, first aired in 2013 and ran a second series in 2014.
ITV said the finale is its most-watched show this year, along with Britain’s Got Talent, which also launched with 8.7 million viewers on Saturday night. Before this, Coronation Street was was the most-watched show with 7.5 million viewers.
Britain’s Got Talent aired between 8pm and 9.25pm, and took a 42.4% share of the total audience. When excluding ITV +1, 7.9 million people tuned in, a 38.8% share. Last year's opening show pulled in 8.8 million people, a 40.3% share.