All of us who enjoy Regency or Victorian romances are willing to suspend disbelief to a certain extent when it comes to steamy illicit sex between the hero and heroine. We know that aristocratic English maidens were not actually behaving the way they do in our favorite novels.
This book, however, asks too much: a clergyman's widowed daughter has sex with a total stranger in the middle of the crowded exhibition at the Crystal Palace. And goes back for more the next day. And the next day. Not only is this a ridiculous premise, the sexual encounters themselves are quick, rather rough, not the least bit romantic, and described in crudely graphic language.
The hero, if he can be called that, is delighted because he's finally found a woman who can take all of his huge cock. I don't know if the method described is physically possible, but it didn't sound like all that much fun.
Once the heroine discovers that her man is actually engaged to her cousin (there's blackmail involved), there's actually a half-way decent story going on, but it's not worth reading the book to find out how it all ends.