While BBC4's The Long Walk to Finchley dramatised ten years in the young life of future Prime Minister Margaret Thatcher, Mamma Mia! director Phyllida Lloyd here bravely tackles the whole thing, told in smash-and-grab flashbacks from Lady Thatcher's amnesiac dotage. Meryl Streep, with disarming conviction and entertaining panache, plays her at various stages of adult life, and is gregariously supported by Jim Broadbent as the ghost of her late husband Denis. This could, in the hands of talented screenwriter Abi Morgan (TV's The Hour), have been a fascinating chamber piece about love in old age. Instead, while dutifully ticking off the key historical events - the Falklands, the miners, the Brighton bombing, etc - the movie fails to find purchase on any broader motivation, beyond that of quasi-feminist megalomania. Beyond the fun of playing spot the MP (and spot the character actor), it lacks the focus of a comparable biopic such as The Queen. Without the Oscar-winning Streep, it's just high-quality biographical karaoke.