During the game, each of the participants was asked to pick from a number of different boxes, one of which had the word "tattoo" on the inside - and whoever picked that box was obliged to have the inking done on TV.
The other band members and James all watched on as Harry had the tattoo inked on his left arm.
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Meanwhile, Harry has sent fans into a panic that he could be about to embark on a solo career, after registering four new solo tracks with ASCAP, the American Society of Composers, Authors and Publishers.
Already Home, Coco, Endlessly and 5378 Miles have all been written with Snow Patrol guitarist John McDaid and the songwriter/producer Gary Go but Harry is listed as the only performer.
-Bang! Showbiz