128 years after the circle line was completed, the capital now has a new orbital railway.
The final section of the London Overground - between Clapham Junction and Surrey Quays - has been completed and the line now runs in a full circle around the capital.
Today, the Mayor Boris Johnson climbed aboard for the official launch, joined by our Political Correspondent Simon Harris.
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David Cameron said the Met proved it can "do more with less" and declined to criticise the Mayor of London for his water cannon spend.
A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.