Rubik's cubes were popular in the 1980s, but they really didn't hit their stride until the old six-color model was abandoned and replaced with some human interest. It's boring to just sort colors -- 3x3 colored blocks are hard to get emotionally attached to. It wasn't until some brilliant toymaker stumbled upon the idea of placing Lady Di's smiling face on one side and Prince Charles' on the other that the Rubik's cube finally made an emotional connection with its audience, surfing into the history books on a wave of popularity.
OK, we made up that story, but the commemorative Rubik's cube really does exist. Some royal memorabilia is tasteful. Some shamelessly panders to the fads of the time. We'll leave it to you to decide which camp the 1981 royal wedding Rubik's cube belongs to.