Malice at the palace : a Royal Spyness mystery / Rhys Bowen.

Enhanced descriptions from Syndetics:

From the"New York Times" betselling author of"Queen of Hearts"comes another mystery for "fans of P.G. Wodehouse looking for laughs mingled with some amateur sleuthing." ("Publishers Weekly")

Lady Georgiana Rannoch won t deny that being thirty-fifth in line for the British throne has its advantages. Unfortunately, money isn t one of them. And sometimes making ends meet requires her to investigate a little royal wrongdoing.
While my beau Darcy is off on a mysterious mission, I am once again caught between my high birth and empty purse. I am therefore relieved to receive a new assignment from the Queen especially one that includes lodging. The King s youngest son, George, is to wed Princess Marina of Greece, and I shall be her companion at the supposedly haunted Kensington Palace.
My duties are simple: help Marina acclimate to English life, show her the best of London and, above all, dispel any rumors about George s libertine history. Perhaps that last bit isn t so simple.
George is known for his many affairs with women as well as men including the great songwriter Noel Coward. But things truly get complicated when I search the Palace for a supposed ghost only to encounter an actual dead person: a society beauty said to have been one of Prince George s mistresses.
Nothing spoils a royal wedding more than murder, and the Queen wants the whole matter hushed. But as the investigation unfolds and Darcy, as always, turns up in the most unlikely of places the investigation brings us precariously close to the prince himself."