Kent Police was called to a report that a man had been assaulted outside an address in New Street at 1.15pm on Thursday 6 October 2022.
Officers attended along with South East Coast Ambulance Service and an air ambulance and a man in his 40s was flown to a London hospital with a serious head injury.
A 41-year-old man and an 18-year-old man, who are both from the Folkestone area, were arrested later the same day on suspicion of assault.
Detectives from the Kent and Essex Serious Crime Directorate are investigating and urge anyone who witnessed the incident, has dashcam footage of an altercation in New Street, or who has any other information to call 01843 222273, quoting reference 46/193708/22.
You can also call Crimestoppers anonymously on 0800 555111 or complete the online form.
