This handsome coin commemorates the wedding of the Prince of Wales and Lady Diana Spencer.
Artist depicting Prince Charles and Lady Diana was Philip Nathan.
Artist depicting Queen Elizabeth II was Arnold Machin.
"Unknown artist" is appropriate when a work of art is unsigned and a supported opinion about who made it is not available (on Savvy Collector).. "Attributed to" precedes the name of an artist when information suggests that it likely was made by that artist (on Savvy Collector).