During the Battle of Britain, the Hawker Hurricane got the most German kills and the more glamorous Spitfire was tops in the PR department, but there was another significant player in the skies over Britain during those tense times. That other player was the Boulton-Paul "Defiant".
The Defiant started out as a good idea in theory (it had a top-mounted turret with 4 .303 machine guns that could fire rearward so as to wipe out German fighters attacking from the rear.) It wasn't so good, however, if they attacked from the front or top or bottom or anywhere except from the rear, so the Germans caught on pretty quickly and the Defiant soon began being thought of as mostly a failure.
This was far from true, however. It simply was being used in the wrong place at the wrong time. Later, it started being used at night against German aircraft during the London Blitz, with devastating results. Ok, maybe not "devastating." But it did it's part. Moral: don't call a duckling ugly until it matures.
See a film about the Defiant's manufacture, and also see it in action here.
Also on that page (if you go to watch the movie) is a more complete description of this fighter aircraft and its specifications, printed as a comment to the movie.