Dorothy L. Sayers said this quote

Persons curious in chronology may, if they like, work out from what they already know of the Wimsey family that the action of the book takes place in 1935; but if they do, they must not be querulously indignant because the King's Jubilee is not mentioned, or because I have arranged the weather and the moon's changes to suit my own fancy. For, however realistic the background, the novelist's only native country is Cloud-Cuckooland, where they do but jest, poison in jest: no offence in the world.