A winner from Elizabeth Mansfield! Well-written, well-plotted, great characters, and not just the main ones. The book grabbed me from the first page and didn't let go until the last. Plenty of excellent scenes too - for example, the initial accidental encounter between Jan and Ollenshaw, and the concert where Ollenshaw first saw Jan play, but the best by far is the spelunking episode.
This one is close to "as good as it gets" in traditional Regency romance. (But please don't pay attention to the cover illustration - the woman's dress on the cover is wrong - it's from the 1890's, not the Regency.)