No, not Princess Margareth of Connaugh, the later Kronprinsessan Margareta of Sweden, but the tiara has been worn by her granddaughter and namesake, Princess Margaretha, Mrs. Ambler for many years. She - presumably - inherited it from her late mother Sibylla who received it as a wedding gift at the time.
BTW, Princess Madeleine looks a lot like her paternal grandmother Sibylla