You're unlikely to forget those in short viral phenomenon with British politicians losing the head (8)
I believe the answer is:
memories
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for memories that I've seen before include "Thoughts of past experiences" , "Remembered things" , "Reminiscences" , "Remembrances of things past" , "Recollections of past events" .)