From cracked.com

Prince died a day after a beer brewed to celebrated the Queen of England’s 90th Birthday was released. It was named after his song. Dunno if the two events are otherwise related, but it got me thinking.

According to wiki, Prince’s states meaning for the song is “When there’s blood in the sky — red and blue = purple…purple rain pertains to the end of the world and being with the one you love and letting your faith/god guide you through the purple rain”

Purple Reign