Last week, my sister and her husband came to Wyken for Thanksgiving. Any unease about leaving behind their grown children and grandchildren was minor compared to their misgivings about the exchange rate. ‘If I think about it, I’ll be miserable,’ my sister announced, ‘so I’ve decided on a Personal Exchange Rate, where the pound equals the dollar.’ My brother-in-law winced as we loaded the car and headed for London.

It’s always enlightening to glimpse your world through the eyes of others. Thanks to my visitors, I saw Liberty dressed in its Christmas finery. We wandered around like country hicks, gasping at the extravagant beauty, and like hicks, we marvelled at the prices as we searched in vain for the little purses, spectacle cases, tote bags and umbrellas made out of Liberty and William Morris prints, little treasures now deemed too dowdy for Liberty’s sophisticated 21st-century look.

Empty-handed, we made our way to Fortnum’s, via the Burlington Arcade. Again, the sheer beauty of this grande luxe alley left us slack-jawed and dazed. By the time we reached Fortnum’s, newly transformed by a lavish makeover, I felt a burst of civic pride. I was about to proclaim that London at Christmas is truly a miracle of prosperity when my brother-in-law asked: ‘Why aren’t there any cycle lanes in London?’ He had quietly observed the Strand, the Embankment, Parliament Square and Victoria, and seen few stretches of cycle lanes, and even those were never wider than 3ft, slender paths that simply vanished at junctions. Suddenly, cycle lanes became more compelling than Christmas decorations.

Perhaps it’s a seasonal thing. Every year at this time, we write a cheque to the Concordia Foundation, in memory of the daughter of family friends. Serena: clever, beautiful, musical, fun. After university, she taught in China, before coming back to London to work in publishing. Newly engaged, she was riding her bike to work when she was hit by a lorry. She died instantly. The Serena Nevill Award for young musicians is a wonderful tribute, but for her parents and two brothers, the fissure in their family is always present.

For years, I have supplied day-glo vests to the children of my friends and ranted about helmets. In fact, a helmet wouldn’t have saved Serena, any more than it would have saved the writer Emma Foa, who died this time last December when a two-ton cement-mixer lorry turned left at a junction near King’s Cross. Her helmet didn’t save Amelia Zollner, 24, the Cambridge graduate who’d begun her first job in London, another case of a lorry driver who failed to see her in his wing mirror. What would have saved them are cycle lanes and close-proximity mirrors on lorries.

The official statistics are these: one cyclist is killed or seriously injured in London every day, and half of these are hit by heavy-goods vehicles (HGVs), most of which are turning left. I suspect the real number is much higher. It’s a hit-and-run Government that encourages young people to ride bicycles, but doesn’t give them adequate cycle lanes. That waits until EU law requires HGVs to have wide-angle mirrors (2009) instead of requiring them on every HGV that enters London, beg-inning January 1, 2008.

London looks beautiful in its festive dress, and Piccadilly is as glamorous as the Faubourg St Honoré. But between now and Christmas at least 20 cyclists in London will die or be badly injured. That is nothing to celebrate.

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