With his floppy hair and cheeky smile, Catrina Best says people often mistake him for the teenage singer, chase him in the street and have even asked him for autographs.
Admitting he "loves" the attention he gets from girls, Best explained to Closer magazine he plans to begin taking hormones to trigger facial and body hair and is already binding his 32D breasts.
Revealing he'd slept with a boy at the age of 16, he said: "It left me numb. I later realised I wanted to be with girls - but as the male in a straight relationship."
Best was diagnosed with gender identity disorder last year, and while his friends are supportive, his parents are less happy and attempted to "talk him out of his condition."
Best adds: "I haven't started dating yet, but girls flirt with me and I even get chatted up by older women, like Harry does!
"But I want to have my op before I date. Harry gives me the guts to be transgender. I hope he invites me to a gig one day!"
The full feature appears in this week’s Closer magazine, on sale now.
> IN PICS: ONE DIRECTION'S ROAD TO WORLD DOMINATION