• To Sir Phillip, With Love begins mere hours after Romancing Mr. Bridgerton ends, which means that Eloise doesn't know Romancing Mr. Bridgerton's big secret! Her family could have told her halfway through the book, but I decided they wouldn't, just to be cruel. (Not to mention that the logistics for me, as the author, were too daunting...)

• The working title for this book was For Eloise, Wherever I May Find Her, which then changed to The Importance of Being Eloise.

• Eloise's letters (which serve as epigraphs for chapter #2 and on) were written well after I'd finished the book. I wanted to do something fun, along the lines of the Lady Whistledown entries in my previous books, but the muse didn't strike until To Sir Phillip, With Love was well into the editorial process.

• Willow bark contains the same active ingredient as aspirin and is indeed quite useful in reducing a fever.