Commuters will be able to get a direct train from Elephant Castle to Finsbury Park starting Monday May 16.
Currently, those travelling between the stations must change at Blackfriars in a 30-minute long journey.
The new route will run half hourly during peak times, and slash journey times to 21 minutes.
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Chief operating officer Angie Doll of Govia Thameslink Railway, which runs the services, said:
“The new timetable from Sunday May 15 is the starting point for rebuilding our railway, to help our customers get where they want to go while reflecting new travel patterns which have changed significantly, particularly on weekdays.
“Our priority is to support passengers by running reliable services, working closely with our stakeholders to support the economic recovery of both local and regional rail.”
The route will stop at Welwyn Garden City, Hatfield, Potters Bar, New Barnet, Oakleigh Park, New Southgate, Finsbury Park, St Pancras International, Farringdon, City Thameslink, Blackfriars, Elephant & Castle, and Sevenoaks.
The route will be active from roughly 7am to 9.50am and 4.30pm and 7.19pm on weekdays with no weekend service.
The new service has been made possible by joining the Blackfriars to Sevenoaks service with trains that were running between King’s Cross and Welwyn Garden City.