A couple allegedly jumped out a café window and people rushed to clear drains of fallen leaves as flash floods swamped a major road.
The heavens opened in Hampstead at around midday on November 1 with a heavy downpour lasting no more than than 10 minutes.
But it was long enough to clog drains with leaves, leading to "wave after wave" of water "cascading down" South End Road, in South End Green.
Conservative officials from the nearby Camden party headquarters in Heath Hurst Road joined locals outside.
Association agent David Douglas said: "The water was cascading down. There was nothing wrong with the drains, every time it rains a lot, it floods."
Mr Douglas said the rain flows down South Hill Park, Heath Hurst Road and East Heath.
He added: "This time of year it's perfect for flooding because it hits the leaves. The railway tunnel lifts the road so the water can't go down to the bus station, it stays here.
"A few of us went out to clear the drains. A lady wearing wellies was obviously used to it."
Water came up to the Euphorium café where witnesses, including Conservative Party officer Valeriy Vetinov, said they saw a "man and woman climb out of the window" as they were not able to leave through the front door.
Andrew Wood, operations manager at Euphorium, said it was "not company policy to comment".
Abby Kang and Marnie Fox, who work at The Nook, a drinks and bites bar in South End Road, said they were not affected.
"For a couple of moments we were worried. Cars were driving through it and it looked like wave after wave crashing and getting higher, " said Abby.
Marnie added: "It's going to be raining all tonight and tomorrow and I'm working in the morning so I hope it will be ok."
The Met Office has warned that Storm Ciarán will cross the southern half of the UK during this evening and Thursday.
The forecaster said it was "a fairly normal autumn storm for the UK" on its website.
Met Office deputy chief meteorologist Brent Walker said: “Once Storm Ciarán has passed, the weather over the weekend continues to look unsettled for many with more showers and rain at times.
"Warnings will continue to be updated over the coming days, so it is important to stay up to date with the Met Office forecast in your area.”
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