Royal Flush by Rhys Bowen

It's the 1930s in England. Lady Georgianna is 34th in line to the throne. And contrary to public perception, she is not rolling in the dough. When her misguided attempt to earn some money almost blows up in her face, she is shipped off to her brother's estate in the country. On her way there, she's asked by the secret service to help figure out who is behind a plot against the royal family. And so begins the lighthearted romp Royal Flush. This is part of a series of which I have not read the rest. But the story was an enjoyable read that could stand on its own--featuring a little humor, a little romance, a little adventure and actual historical figures (ie, Wallis Simpson and a young Queen Elizabeth)flitting about.