Siobhan Finneran loves playing the bad girl on 'Downton Abbey'.
The actress has ''great fun'' portraying bitter spinster Sarah O'Brien on the ITV1 period drama and has invented a tragic back-story for her alter-ego because she believes she is secretly soft at heart.
Siobhan said: ''I actually have great fun being sniffy to everyone! I love O'Brien the most when she's spiteful and has a brilliant put-down. She's a clever lady and a bad enemy to make. Some people think she was just born bad, but I believe that at some point she has had some damage done to her.
''I have invested a back story for her, although whether that matches what [creator] Julian Fellowes had in mind, I'm not sure. The fact she had a nephew and family came as a surprise.''
The actress hopes viewers will get to see a different side to Lady Grantham's cunning maid in the future and thinks some romantic interest would provide great comedy.
Siobhan added to The Sun newspaper: ''O'Brien with a boyfriend would be stupendous! Who would be brave enough to take her on a date? Kevin Doyle, who plays Joseph Molesley, and I are always speculating what our characters would be like on a date - it would be hilarious.''
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