We were up town yesterday. Princes Street has lately taken to having little video adverts on the bus stops - not a huge improvement to the joy of life, in my opinion, but anyway. And all the way along the street, we saw Keira Knightley advertising Chanel perfume. "It's funny," mused Mr L. "Her mum would never have expected her daughter to appear on every bus shelter in Princes Street."


By which he meant that the girl we knew when we were young - the pretty girl who was part of the local crowd at the badminton club (and who grew up to be Keira Knightley's mum) presumably never expected to have such a famous - and exceedingly rich -  daughter.


Keira's mum was nice enough, though not one of our particular friends. She was very pretty, but in a slightly broad-hipped, thick-legged way. I assume that Keira takes after her dad in body shape.


It's odd how things turn out. The family who lived across the road from us when our children were small were extremely nice but utterly normal. You would have put money on their never doing anything particularly unusual. The parents were very devoted to each other and the children; and the son and daughter were really lovely young people: sweet and slightly shy but very charming. Yet within a few years the daughter of the house had become a tv presenter, appeared scantily clad in lads' mags, had her naked image projected on to the Houses of Parliament, married and divorced a famous pop singer, become bald and bipolar and had more or less (though not totally) sunk from sight. Meanwhile the parents split up, the father became alcoholic (possibly the former as a result of the latter) and the mother had died of cancer.


And it's interesting to see what the girls who were in my class at school have done with their lives. It was a selective girls' school, so most of us were together for 13 years and I'm still in touch with quite a few of them. We were all in the top stream, so all reasonably clever. One became a professor of agriculture and advisor to the government. One, a good friend of mine, had a very important job in the museum world, sadly developed dementia in her 50s and has recently died. One achieved great success in business. (None of these successful women had children; two didn't marry at all and one married late in life. I imagine that this is relevant to their achievements in the wider world.)


One, another of my particular friends, was knocked down and killed in Brussels as she walked along the pavement, at the age of 23. Unbelievably, another member of the class also developed dementia some years ago, though is still alive - just.


And, as you would expect, a lot of us have been teachers and librarians and accountants and mothers, never making a big splash in the world. Some really bright girls never worked at all after having children.


But back in the 60s, you wouldn't really have been able to predict with certainty which of us would be the high-fliers. Nor had Mr Life and I any idea that we were sharing a badminton court with the mother of a famous film star or allowing our children to play with someone who would become a slightly infamous ladette.


Strange thing, life.