David, The programme Who Do You Think You Are on the Walker family from the Coolattin Estate, gave the impression that all the Fitzwilliam Papers are held in Sheffield. The National Library of Ireland has a very large collection of the Estate Papers from the early 1700s. They are an invaluable source for information on families who lived on the estate. The papers which are in Sheffield are partly indexed online. They are not online nor are they indexed online, so have to be searched in person. Jane