Observations: Just a Mo for Julie Walters

The film Mo – a new biopic about Dr Marjorie "Mo" Mowlam – boasts the perfect actress for the title role. Julie Walters, 59, gives an uncannily accurate performance as the former MP for Redcar – she captures everything from Mowlam's slight speech impediment to her pigeon-toed, backwards-leaning, chest-thrust-forward gait.

Neil McKay's drama follows her through the highs of New Labour's landslide election victory in 1997 and Mowlam's triumphant stewardship of the Good Friday Agreement, as Northern Ireland Secretary, the following year. In an era when, thanks to the expenses scandal, MPs have never been more loathed, it is refreshing to be reminded that not all politicians are of the same stuff.

But the film does not ignore the very considerable lows of Mowlam's life. She is unceremoniously ejected as Secretary of State for Northern Ireland in 1999, and discovers she has a brain tumour.

Walters tells me: "She is the one politician of recent times whom everyone has heard of, whether or not they know anything about politics.

"Mo was fascinating and totally unique. As soon as I became aware of her in 1997, I fell in love with her."

Mo is on Channel 4 on Sunday