In the last 200 years 2 women have sat on the British throne for two thirds of the time - Queen Victoria and Queen Elizabeth II. They lived in a dangerous world, reigning over the rise and fall of empire, dodging assassinations, and surviving family scandal. So what is the secret of their royal success? Just look at the numbers. Victoria puts her image on the world's first postage stamp, the Penny Black, 68 million of which will be printed in her lifetime.  Elizabeth will invent the "walkabout" and will visit 110 countries in 6 continents, racking up 1 million miles.