This Margaret Thatcher biopic deserves to be seen for Meryl Streep’s magnificent, Oscar-winning performance in the lead role.

Significantly, she portrays Thatcher not only in her prime ministerial heyday, but also shows the former leader struggling with the onset of dementia in lonely old age.

She is visited by daughter Carol (Olivia Colman) and benignly haunted by hallucinations of her dead husband, Denis, played with puckish humour by Jim Broadbent.

What we see of Thatcher’s political career is told entirely from her own point of view, as filtered through the dimmed lens of her Alzheimer’s-stricken mind.

So we flit back and forth through the key events of her life, from her struggle as a young lower-middle-class woman (superbly played by Alexandra Roach) to gain a foothold in the stuffy post-war Conservative Party to the highs and lows of her political career, including her 1979 election victory, the Falklands War, miners’ strike and the Brighton bombing.

The lack of dissenting voices will annoy some, as will the lack of political bite, yet in the end the film slips free of party political shackles to offer a moving portrait of loneliness, dotage and decline.