I think we need to write to Debretts David Williamson is now dead to ask if they actually had sight of the Letters Patent otherwise I would find it hard to accept their assertion It would effectively mean that his eldest daughter had a fundamental right to call herself and be referred to in all legal documents as Baroness or Lady Home of Berwick But in fact there is not one document  notably her Testament  that I can find that refers to them as such Merely as his daughters with the honorific Lady because they were daughters of an Earl In addition Debretts cannot settle these issues Did Alec DouglasHome make a claim in The House for that Peerage to be added to his stable Because that seems to be what theyre saying Frankly I would treat such a suggestion with disbelief