Arriva will take over as the operator of the London Overground services from November 2016 including all the Overground services through Hackney.  The franchise will operate for 7 1/2 years with a possible additional two years.

The announcement includes news of:-

• Modernised stations
• More frequent services starting with the North London line
• New trains on the Overground routes out of Liverpool Street from 2018
• New trains on the Gospel Oak to Barking line from 2018

https://tfl.gov.uk/info-for/media/press-releases/2016/march/arriva-named-as-new-operator-for-london-overground