Her name appears in The Peerage at http://thepeerage.com/p29760.htm#i297594
about the middle of the pagehttp://www.william1.co.uk/L3.htm
has pedigree and possibly more infohttp://web.ukonline.co.uk/members/tom.paterson/ogrady4.htm
gives her father's name
Hope this helps.
Have you run across a Francis de Courcy Grady born about 1806 in Canada or New York? He is my gr-gr-grandfather, whom I cannot connect to the O'Gradys. Thanks