Rob Blackhurst

In the opening scene of the Iron Lady, a long retired Margaret gives her minders the slip and shuffles off to the corner shop to buy a pint of milk. Hunched in a regulation pensioner overcoat and headscarf, she dips an arthritic hand in her purse and pulls out her money with lumbering concentration, as if all is alien.

Within the film's first few seconds the symbolism has reached Geiger counter levels. Loss of power and decrepitude has seen the proud honey bouffant replaced with a washed-out headscarf. The disciple of sound money is having problems counting real money. She is returning to a grocer's shop- the central metaphor of her political career – but this isn't the familiar world of Alf Robert's store in Grantham. A twenty-something, i-pod headphones plugged in, waits impatiently behind her, irritated at being held up by another faceless pensioner in a queue. She is plunged in a world that she no longer recognizes, or recognises her.

With the help of a prosthetic bird-of-prey nose her own piercing blue eyes and well-observed partridge steps, Streep goes beyond impersonation to physically become Thatcher. But the brilliance of the performance hides something that jars: Thatcher recast as a Boadicea who tramples all men under foot. She was never a proto-feminist, and certainly would not have expressed such views in the early 1950s. The most didactic revisionist scene comes when she tells a brylcreemed Denis, pre-wedding, that he shouldn't expect her to do the housework. In reality, Thatcher took delight in buying Denis's favourite sausages and dusting the light-fittings in the cabinet room. She regarded work of all kind as a virtue, whether it was cooking bland shepherd's pies for her cabinet or filleting cabinet papers.

Later, Streep's Thatcher watches a home movie of her children playing on the beach, full of regret for the family life that she missed. Perhaps in the twilight years of dementia she has regretted her maniacal work ethic, but in post retirement interviews she was always candid enough to stand by the choices she made. Altogether, despite the protests from her acolytes, the Iron Lady is a deeply flattering portrayal. Streep's whisky-swilling Thatcher is more humane and more humorous than the real model ever seemed. And, even her late period siege mentality is excused. In a characterization she would have surely hated, her flaws (or strengths) are medicalised. Her handbagging of Geoffrey Howe in Cabinet are not seen as cold hubris but the first signs of dementia, possibly brought on by the shock of the Brighton bomb.

The broad-brush strokes of the film give a very fuzzy sense of chronology. Perhaps we are seeing everything through the lens of dementia but for historians the fast and loose timescales and historical detail will grate. The miner's strike of 1974 morphs into the winter of discontent of 1979, with uncollected bin bags blocking the streets. The 1979 election campaign is suddenly invaded by BBC micro graphics from the 1987 campaign. And poor Michael Foot, anti-fascist and supporter of the Falklands war, is transformed into to a long-haired peacenik. The Iron Lady might have been better if they had the courage to stay with the dementia theme without inserting archive footage of Thatcher's greatest hits – from the sinking of the Belgrano to doing business with Gorbachev.

Despite the brilliance of Streep's portrayal, the Iron Lady's best scenes are the flashback scenes with a young Margaret in early 1940s Grantham. She drinks in her father's expectations with a kind of eye-popping intensity, braves the Lutftwaffe to saves the butter from destruction during an air-raid, and carries on with a kind of piety and self-belief that would soon impinge on lives beyond the flat plains of Lincolnshire.