The new London Overground extension between Dalston Junction and Highbury & Islington is set to open next week, over two months ahead of schedule.
The official opening of the new section is not expected to take place until 28 February, but passengers have reported that limited train services have already been running on the route.
A commuter said said: “I was surprised to see no trains when I arrived at Dalston Junction this morning because they usually stop there to turn around and pick up passengers. Then I realized that trains were coming through from Highbury already which was a nice surprise.”
A TfL spokesman said that the official line was that no services were yet running on the new extension.
The extension will form an integral link between the East London line and the rest of the Overground network, meaning that it will be possible to travel all the way from Croydon to north-west London.
The opening of the service will also create a continuous orbital railway around the capital.
There will be a reduced service from midday on Sunday 27, with a full service running from Monday.
Currently, passengers wishing to continue their journey from Dalston Junction to Highbury and Islington have to walk 200 yards to Dalston Kingsland station. The new section of line will improve journey times for passengers by eliminating the need to change trains.
However, passengers wishing to continue their journey past Highbury and Islington will need to change trains.
Most of the renovated East London Line was opened in May 2010, but the spur connecting Dalston Junction was due to open in May 2011.
The opening will mark the completion of phase one of the East London Line Extension project. Phase two of the project, due to open in time for the 2012 Olympics, will extend the line from Surrey Quays, via Peckham and Battersea, to Clapham Junction.