Pay no mind to that person, I think you did perfectly well on this. Plus, being British is no legitimate reason to be offended by something that they think isn't to their "standards." I kind of laughed when I saw that "I'm British and I find this offensive" XD Keep up the good work ♪( ´▽`) Plus, the eyebrows look perfectly fine; nothing needs to be drawn in the original artist's style; if it did, every piece of art would look the same, and that'd be quite boring, yes? Besides, I prefer the way you drew his eyebrows to the way they're usually drawn; yours look much more realistic, which is a quality I adore.
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Happy aniverury Arthur!