Line Of Duty’s Polly Walker: I didn’t watch the series

She also said she was kept in the dark about the full depths of her character’s involvement until near the end of the season.

Line Of Duty actress Polly Walker has admitted she did not watch the hit series – despite her alter-ego Gill Biggeloe being unmasked as the “snake in the grass”.

The discovery that her lawyer character was corrupt had more than nine million viewers glued to their sofas, making Line Of Duty the biggest show of the year so far.

But actress Walker, who was kept in the dark about the full extent of her character’s involvement until near the end, revealed that she steered clear of the series.

“I knew two episodes before what was happening. I knew she (Biggeloe) was up to no good,” she told ITV show This Morning.

“But I didn’t know to what extent she was a snake in the grass.”

She added: “I’ve always known that Gill was a ‘bad’un’ on some level but I didn’t know to what extent.”

And she added of the BBC One series, also starring Vicky McClure, Martin Compston, Adrian Dunbar and Anna Maxwell Martin: “I didn’t watch any of it.”

Asked whether she tuned into the finale, she said: “No I didn’t. I went to a friend’s birthday party.”

She said the show was “brilliantly written” and “doesn’t patronise the audience” but it was “quite nice… to watch everybody else enjoy it,” adding: “I know what’s happening, so on some level the excitement is different.”

The tense final episode attracted an average audience of 9.1 million, a 44.1% share, with a peak of 9.6 million viewers on Sunday night.

It makes the drama, on the activities of police anti-corruption unit AC-12, the most popular show of 2019 so far, based on overnight figures.

The figures are also the highest for a drama since Bodyguard, also created by Jed Mercurio.

The finale to that hit thriller, starring Keeley Hawes and Richard Madden, drew a higher overnight audience – of 10.4 million and a peak of 11 million in 2018.

The BBC has ordered a sixth series of Line Of Duty and Walker said she had no idea whether she would be in it.

“I think everything is up for grabs. I don’t think anybody knows, apart from the puppet master Jed Mercurio…” she said.

“This is my theory, Gill is such a survivor, she won’t be playing sudoku in her sitting room for too long. She’ll be looking for ways to survive.”

And she added: “Gill’s alive. I thought she was going to die, but no.”

The BBC said that Sunday night’s Line Of Duty was “the biggest overnight rating for the series ever”.

It was also “the most watched show of the night, across all channels, as well the biggest overnight rating of the year so far”.

Figures are expected to grow once consolidated numbers – programmes recorded and watched up to seven days later – are taken into account.

BBC director of content Charlotte Moore said: “Over the past six weeks, Line Of Duty has kept the whole nation on the edge of their seats, so it was fantastic to see such a big audience for Sunday’s finale.”

All five series are currently available on the BBC iPlayer.