I found this lovely Folio edition of T H White’s volume of Regency gossip, The Age of Scandal, at Lambdha Books in Wentworth Falls.
Other forms of personal toughness were connected with the childish ‘dare’. Mytton drove a chaise across country, by night, over hedge and ditch, until it collapsed: he jumped the iron railings of his park: he introduced a live bear at a dinner party: he galloped over a rabbit warren to see whether his horse would fall, which it did: in the end, to cure the hiccoughs, he set fire to his own night-shirt, and burned himself to death. It was to prove that he was not afraid.
– T H White, The Age of Scandal
(note: Wikipedia’s entry for Mytton upholds the story of the nightshirt but denies that he died of the burns it caused.)