I've always loved Dorothy Sayers, but I'd not revisited this one since college and it's a much stronger novel than I'd remembered. What I missed back then was that the fast-living young louts aren't the stereotypes that Sayers occasionally drops into her texts when she isn't paying attention: they are the bright young things of Waugh's Vile Bodies, which appeared three years before this Sayers mystery.
As is often the case in Sayers, the crime is absurdly complex and overwrought. The chance to view the insides of a 1930's London advertising office is valuable; in fiction, we see far too little of the modern workplace. Lord Peter, for all of his impossible gentility, is a wonderful character, and Sayers has a delightful ear.
I haven't asked him yet. How can I? It's horribly hampering to one's detective work when one isn't supposed to be detecting, because one daren't ask any questions, much.
Oh, that last word works wonders.