A woman lay unconscious on the floor for several minutes after being punched outside a Hoxton nightclub.
The assault took place on June 14 2015 in Drysdale Street at 4.45am.
The 30-year-old victim was punched as she left the club and hit her head on the ground as she fell.
She was taken to an East London hospital where she received 20 stitches to her lower lip and several staples to a head injury.
Police have now released a CCTV image of a man they want to speak to in connection with assault.
He is described as between 25 and 30 years old, 5ft 8ins with short brown hair. He was dressed in a black T-shirt and blue jeans.
Police are keen to hear from anyone who recognises the man or who witnessed the assault.
Anyone with any information is asked to contact Detective Constable Sophie Hayes from Hackney CID via 101 quoting reference number 4614922/15 or Crimestoppers anonymously on 0800 555 111.
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