The Baroness Blackstone, British Library chairman and trustee of the Royal Opera House, was among the speakers at a reception the other day hosted by the New England Historic Genealogical Society, where she talked about preparations for the 800th anniversary celebration of the Magna Carta. (That’s in 2015, remember.) Guests included Margaret Lowe, president of the Daughters of the British Empire, Janet Spitz of Boston Public Library’s Leventhal Map Center, and genealogical society CEO Brenton Simons.