4.85 The inner section of the Great Northern Line serves a number of busy commuter stations in North London and Hertfordshire. Many respondents to the consultation were concerned about the impact of the Thameslink Programme and the new TSGN franchise on services to Harringay and Hornsey and on destinations on the Hertford Loop. There were also calls for increased frequency into Moorgate in the off-peak, and for services later into the evenings, and at weekends, to serve Moorgate rather than diverting to King's Cross.
4.86 The Department took careful account of the concerns raised during the consultation in putting together the train service requirements for the franchise, which offer significant benefits to customers using inner stations on the Great Northern line.
December 2015 onwards
4.87 From December 2015, trains running via Finsbury Park will no longer be diverted to King’s Cross at certain times but terminate at Moorgate, where the extended opening times will broadly match those at London Overground stations. This recognises the increased activity late at night and at weekends in the Old Street / Moorgate area, and allows customers to take advantage of the improved interchange with the London Overground services at Highbury & Islington.
https://assets.publishing.service.g...a/file/245205/consultation-responses-tsgn.pdf