The Popular edition below is some 40% longer than the Harlequin. It isn't dated but the young miss looks 1960s rather than 1760s and the flag on the cover puts it after 1965. The back cover blurb ("FIRST TIME IN PAPERBACK") is wrong but it may be the first unabridged paperback edition.
Harlequin 196 - November 1952
Harlequin 196 back
Popular 95-202 - nd
Popular 95-202 back