She was a small, pretty woman with chintzy blouses and a nervous habit of clearing her throat. A stiff leather handbag hung like a weapon over her arm; if a wisp of hair escaped from the helmet of her coiffure, she fiddled with it anxiously. In mid-campaign, she was given a grubby calf to hold and didn't know what to do with it. Our first views of Margaret Thatcher weren't reassuring.

Yet it was la différence that underwrote her astonishing success. The unthinkable – a woman prime minister – had been made flesh. Suddenly anything seemed possible. I was a city councillor in Birmingham with two small children. I knew, with total certainty, that if she could do it, then so could I.

Mrs Thatcher learnt very quickly to turn her outsider status to...