Hampshire Police said they arrested a 54-year-old man for spray-painting a postbox in Lymington, where Olympic sailor Ben Ainslie lives.
Rob Smith told the BBC he painted the postbox in Lymington High Street gold to mark Ainslie's latest gold medal - his fourth.
He said he thought it was "madness" that an official postbox had only been painted gold in Cornwall, where Ainslie grew up. He told the BBC: "He's lived here for around 15 years, all of Lymington believes that the Post Office made the wrong choice in painting one down in Cornwall - give him two. I did it because I'm a passionate sportsman, I think the Olympics have been brilliant. Ben's achievements have been outstanding."