The Masqueraders by Georgette Heyer

By the afternoon the news was all over town that Fanshawe had wounded Rensley in a duel that had taken place that morning in Galliano's rooms, of all places in the world. Every sort of tale was told. Fanshawe had taken leave of his senses and struck Rensley across the face with his glove: no, it was Rensley struck Fanshawe; faith, it must have been that way, for everyone knew that it was not like Fanshawe to pick a quarrel. The affair had sprung up out of a clear sky: there had been some raillery which Rensley took exception to, and Fanshawe had carried it too far.

Mr. Belfort heard it from my Lord Kestrel, and was thunderstruck. My lord told it him between chuckles and with many embellishments, and described, with gesture, the thrust that had put Rensley out of action for many weeks to come. Mr. Belfort went hurrying off to confer with Mr. Devereux, whom he found writing execrable verse to a lady of uncertain morals, and bore him off straight to Arlington Street.