Happy Valley actor Robert 'Con' O’Neill said when he read the script for the last episode of the hit BBC series it "blew" his mind as he promised the ending of the show will be "extraordinary".

The final episode of the show, created by writer Sally Wainwright and starring Sarah Lancashire as West Yorkshire Sergeant Catherine Cawood, will be broadcast on Sunday night at 9pm.

For two series of the show, O’Neill has played recovering alcoholic Neil Ackroyd, who is the boyfriend of Catherine’s sister, Clare, played by Siobhan Finneran.

When he was asked about the ending on This Morning on Thursday, O’Neill said: "When I read the script for the last episode it blew my mind … Sally has written an extraordinary ending to the show."

Over the last five episodes, Happy Valley has continued to follow the story of Catherine, who is currently awaiting retirement, and her nemesis, the murderer and sex offender Tommy Lee Royce, played by James Norton, along with introducing new plotlines and characters.

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The six-part drama has also focused on Catherine’s grandson Ryan, played by Rhys Connah, and his relationship with his father Royce, the crime family the Knezevics and married couple Game Of Thrones star Mark Stanley and former Coronation Street actress Mollie Winnard.

Stanley plays Ryan’s controlling PE teacher Rob Hepworth, who padlocks the fridge and beats his wife Joanna, who is addicted to diazepam, which has been provided by Faisal Bhatti (Amit Shah).

O’Neill said he missed the impact the final series was having on audiences as he was away filming romantic pirate comedy Our Flag Means Death, which also stars Rhys Darby and Taika Waititi.

He added: "So I was in New Zealand and then in LA and then came back and as soon as I got off the plane here (people were whispering when I was) waiting at customs.

"I’m getting some bizarre DMs and (my mates are) texting me with ideas about who he is and what’s going to happen…

"We’ve lived with this show for a long, long time and for Sally to bring it home the way she has, it’s very easy to keep a secret because it’s just beautiful … and isn’t it wonderful to not have a show dropping every episode?"

You can catch the finale of Happy Valley on Sunday at 9pm on BBC One.

Source: Press Association