BP Defiant's "big day" at Dunkirk

I’ve read a variety of claims about the one day (supposedly) during which Boulton Paul Defiants scored the kind of victories for which they were designed, ranging from 28 to 37 kills on 29 May 1940, during the Battle of Dunkirk, for the loss of one gunner.

Does anybody have any information about this day, Defiant-wise, that seems solid?

Another question: It’s also often said that very early in the Defiant’s career, Bf-109 pilots attacked Defiants in a classic pursuit curve from the rear, thinking they were bouncing a Hurricane. Is there any evidence that this is true, namely a Luftwaffe pilot who actually admitted that, or is it just a surmise?