As dusk and cold drizzle fell across the banks of Canary Wharf and the City of London yesterday, traders and other financial workers filtered out of their offices in a steady stream and headed straight for the bars around their workplaces.

For those in Canary Wharf, above their heads, the bright orange stock ticker on the Reuters building – to which the same workers had raised their glasses in jubilation in happier times – displayed downward arrow after downward arrow. It served as a depressing reminder of what they had just just witnessed.

Terry Chamberlain and Tim Burland, traders for Worldwide Currencies, which organises large international money transfers, sat amidst the hordes of other suited city workers. Both are barely 30, but look tired and haggard. "It's been pretty stressful – that's why we're in here having a drink on a Monday night," said Mr Chamberlain. "We've got guys who have been at our organisation for 30 years watching the news and feeding the developments straight to us. But I don't think they'd ever seen anything like it, everything kept changing in a heartbeat.

"The market was just so volatile, it made everything really hard work. We specialise in beating banks and other brokers, so we have to keep very tight to the market. If we quote tighter than anyone else, and then it suddenly moves, we have to be really careful, because we could lose out big time if we're not on the ball.

"You spend ages building up good relationships with clients, and they are relying on us to get them out of there before it moves. But when something like this happens, they start losing money right away, and when you try to get through to them it was engaged. I had to make about 150 calls as fast as I could. But it's all good fun, that's why we work here."

For Mr Burland, predicting the day's rapidly changing movements proved to be almost impossible: "I was watching the dollar, and ... it moved a cent in three minutes."

In the other bars and public places around London's financial centre, city workers huddled together in groups, unwilling to talk publicly about their fears for the future. One says he is afraid that his comments might inadvertently make things worse.

In another part of London, Hugh McAllister, from the investment bank Kaupthing Singer & Friedlander, did his best to remain upbeat and philosophical about what he had witnessed. "It was a difficult, long day really. And it certainly wasn't very pleasant. Obviously, we've seen one of the biggest falls for ages. But I suppose it was bigger than people expected. We've had quite a few of these days recently."