Octavius and the Perfect Governess by Emily Larkin

A governess in jeopardy . . . and the marquis’s son who goes undercover as a housemaid to protect her.

Lord Octavius Pryor leads a carefree and untroubled life, until the night he visits Vauxhall Gardens in the guise of a woman.
At Vauxhall, Octavius discovers that being a female is very different from being a man. Annoyingly different, unpleasantly different, and—when he encounters the lecherous Baron Rumpole—dangerously different.
Determined to teach the baron a lesson, Octavius infiltrates Rumpole’s household, where he meets the woman of his dreams: Miss Toogood, governess to the baron’s daughters. Suddenly Octavius has three pressing tasks. 1) To teach the baron to keep his yardstick in his breeches. 2) To keep Miss Toogood safe. 3) To convince her to marry him.