Mary Dawson, Countess of Dartrey
Mary Frances Dawson, Countess of Dartrey, 24th Baroness de Ros of Helmsley , was a British peer. She was born in London. Her parents were The 23rd Baron de Ros and Lady Elizabeth Egerton. Upon her father's death in 1907, Mary succeeded to the title.
The 24th Baroness married Anthony Dawson, 3rd Earl of Dartrey, in London on 2 October 1878. To them were born three daughters; the Barony of de Ros descended among their issue:
