From the moment I first worked for Margaret Thatcher, almost exactly half a century ago, it was obvious that she was different from any politician I had met. She was strikingly pretty for one thing, more like a milkmaid than an Iron Lady. And she sounded cross, as if she was not being told the whole story. At first I thought this was because her voice was a semitone higher than it later became. In my patronising way – I was all of 25 – I thought she might be a bit nervous because this was her first front-bench post...