The image appeared in a children's anti-racism booklet distributed in primary schools in the local area about the life of former footballer Paul Canoville, who was the first black player to play for Chelsea.
It shows a cartoon figure wearing a white hood and robes, which is typically associated with the white supremacist group, with the outfit also bearing Millwall's crest.
Makes sense, I assume the club shop owns the rights to this outfit and it's being sued for copyright infringement?