To be a true Cockney you have to be born within the sound of Bow Bells. And, despite what most people think, Bow Bells aren't in Bow. They are in fact the bells of the church of St. Mary-Le-Bow, Cheapside, in the City of London. Recent research has suggested that, given the right atmospheric conditions and an absence of traffic noise, the sound of St. Mary-Le-Bow's bells could have been heard up to five miles away, even out as far as Bow itself. But no longer. Presumably there were a lot more genuine Cockneys around hundreds of years ago than there are now.
Back in the 14th century the bells of St Mary-le-Bow rang out a curfew across central London at 9 o'clock to warn the locals that it was time for bed. These are the bells that Dick Whittington heard in 1392 that made him 'turn again' (he was real, by the way). The bells were (you won't be surprised to hear) amongst the many destroyed in the Great Fire, but were also (you will be surprised to hear) silenced for two years in 1856 by an eccentric local woman who believed that the noise of their clanging might otherwise kill her. The BBC used the peal of Bow Bells at the start of every one of their broadcasts to occupied Europe during World War II, but that didn't stop the bells being destroyed yet again in the Blitz of 1941. A new peal of 12 bells was installed in 1956, each inscribed with a verse from a psalm, and the initial letters of those 12 psalms spell out the name 'D WHITTINGTON'. Ahhh, sweet.
...says the great bell at Bow
