At 11.10pm on Monday 19 April 2021, the victim was reportedly followed into Effingham Street by three men and assaulted by at least one of them.
Officers attended along with South East Coast Ambulance Service and the man was treated at the scene for a head injury.
One of the suspects is described as around six feet tall, of mixed race, with dark brown hair and a tattoo on his right arm. He was reportedly wearing a blue Puma tracksuit.
Another of the suspects is described as around five feet and eight inches tall, black, of large build, with dark curly hair. He was wearing grey shorts, a yellow jumper and black Nike trainers.
Anyone who saw anything suspicious in the area around that time, or who has any information, CCTV or dashcam footage that may assist officers, is urged to call Kent Police on 01843 222289, quoting reference 46/65348/21.