This patch is a one-of-a-kind patch that stemmed from a private joke -- don't bother trying to collect it.  It began when UK announcer Roller Polar Bear's dog, Patch, died.  Two friends thought to cheer him up by creating a special patch for him that included the word WOFTADAR which, when said aloud, is how he pronounces WFTDA with his accent.  For fun he decided to start collecting pictures of famous people in derby holding the patch -- I've seen shots of Bonnie Thunders and others holding it -- before announcing the patch (and picture collection) will end on March 30, 2019 when he makes a collage of all the patch pictures with the WOFTADAR patch next to them.  You can hear the story for yourself on this podcast starting around the 42 minute mark.