Although the collection has been given the general title of Nannau Manuscripts, the collection includes papers not only relating to the original Nannau family, but also those of the Vaughans of Hengwrt and Dolmelynllyn, and the assembled papers regarding the Meillionydd lands in Lleyn and Ystumcolwyn in Montgomery.
A collection of 2972 items consisting of the papers of the Nanney family of Nannau, Dolgellau; the Vaughans of Hengwrt and Dolmelynllyn, co. Merioneth and those relating to the Meillionydd (co. Caernarfon) and Ystumcolwyn (co. Montgomery) estates which were added to the Nannau-Hengwrt possessions upon the marriage in 1765 of Sir Robert Howell Vaughan, the first baronet of Nannau, to Anne Williams the heiress of Ystumcolwyn. The Nannau-Hengwrt group consists of deeds relating to properties in Bodgadfan, Brithdir, Cefnllanfair, Cefnyrowen (Cymer Abbey lands), Cefnyronnen, Ceiswyn, Cerist, Corwen, Dinas Mawddwy, Dolgellau, Dolgledr, Doluwcheogryd, Dyffrydan, Ffestiniog, Garthgynfor, Garthmaelan, Harlech, Llanaber, Llandecwyn, Llanddwywe, Llanegryn, Llanelltud, Llanenddwyn, Llanfachreth (including Cymer Abbey lands), Llanfor, Llanfihangel, Llanuwchllyn, Llanycil, Llwyngronw Abad, Llwyngwril, Llystrefelyn, Maesllangedwis, Maentwrog, Mignaint, Nannau (including Cymer Abbey lands), Penaran, Penrhyndeudraeth, Prysor, Talybont, Talygarreg and Trawsfynydd (including Cymer Abbey lands), co. Merioneth; and Aberdaron and Llanfaelrhys, co. Caernarfon, 1420-1902; rentals, 1590, and 1701-1860; miscellanea, including papers relating to the shrievalty of Hugh Nanney, 1626-1627; record books of the Royal Merioneth Militia, 1796-1799; papers concerning negotiations between John Vaughan and prospectors for gold on farms belonging to the Nannau estate, 1895-1898; and correspondence. Also included is a group of documents relating to fisheries in various rivers, namely, Mawddach, Alaw and Llanelltud, 1578-1901.
Personalities represented in the deeds and papers include Gruffydd ap Hywel ap Dafydd ap Meurig Fychan ap Hywel Goch (alias Griffith Nanney I), Hugh Nanney Hen, Griffith Nanney II, Hugh Nanney II, Griffith Nanney III, Hugh Nanney III, Griffith Nanney IV, Hugh Nanney IV, Dr John Davies of Mallwyd, Robert Vaughan of Hengwrt (the antiquary), Howel Vaughan of Vaner, Robert Vaughan II of Hengwrt, William Vaughan of Nannau and Corsygedol, Sir Robert Howell Vaughan, first baronet of Nannau, Hengwrt and Rug, Sir Robert Williams Vaughan, 2nd baronet and John Vaughan of Dolmelynllyn and Nannau.
The Meillionydd papers relate to the estate of the Williams family, members of the Cochwillan branch of the Griffiths of Penrhyn who held Meillionydd in Lleyn for over a century and a quarter in the male line. In this group are deeds, settlements, wills and other documents affecting properties in Aberdaron, Abercin, Bangor, Beddgelert, Bodferin, Bodnithoedd, Bodrydd, Botandreg, Botwnnog, Bryncroes, Clynnog, Cricieth, Dinlle, Dinorwig, Dwygyfylchi, Gelli-wig, Isheli, Llanfaelrhys, Llanfihangel-y-Pennant, Llangwnnadl, Llaniestyn, Llanllyfni, Llanystumdwy, Maenol Bangor, Meyllteyrn, Morfa, Nantgwnadl, Nefyn, Penllech, Penmorfa, Pennarth, Penyfed, Pwllheli, Rhiw, Rhwngdwyfor a Dwyfach, Trebrynbras, Trefaes, Trefan, Tremorfa, Tudweiliog, Ultradaron and Uwch-heli, co. Caernarvon; and Llangristiolus and Llanynghenedl, co. Anglesey, 1534-1779; estate accounts, 1715-1722. Members of the Williams family represented in the papers include, Arthur Williams, M.A., rector of Llanengan; Arthur Williams II, John Williams, Robert Williams, Owen Williams, Edward Williams, Arthur Williams III, Robert Williams II and Arthur Williams IV.
The Ystumcolwyn papers include family papers (wills, settlements, etc.) and deeds concerning properties in Blaenglesyrch, Broniarth, Bryncynfelyn, Castell, Cefn, Cefnllyfnog, Collfryn, Cwm, Cyffin, Garthgelynnen-fawr, Guilsfield, Llanfechan, Llansanffraid, Lledrod, Llwydiarth, Maesllymystyn, Main, Meifod, Nantymeichiad, Peniarth, Rhisgog, Stryd y Vyrnwy (alias Pontyscowryd), Trefnanneu, Trefnant Fawr, Trefnant Fechan, Trewern, Welshpool, Ystumcolwyn and Ystumgynon, co. Montgomery; Abergele, Betws, Denbigh, Llaneilian and St. George, co. Denbigh; and Abertanant, Oswestry and Stockton, co. Salop, 1428-1775. There are in addition groups of deeds and documents featuring the Kyghley family of Cichle near Beaumaris, Anglesey and the Griffith family of Penrhyn, Llandegai, co. Caernarvon, and referring to lands in Beaumaris and Holyhead, co. Anglesey; Bodfaeo, Dwygyfylchi, Gwyrythion (Tref Gwyr-rhyddion) and Llanbedr-y-cennin, co. Caernarvon; and Llaethfaen, co. Denbigh, 1443-1547; William Williams and Henry Williams of Cochwillan and concerning properties in Caernarfon, Conwy, Betws Garmon, Botanreg, Dinlle, Llanllechid and Llechan, co. Caernarfon; Bodlennyn, Llysfaen and Tywynnan, co. Denbigh; Burgedin, Guilsfield and Lledrod, co. Montgomery and Bryn, co. Salop, 1569-1617; papers relating to the tithes of Penmachno, 1597-1757; papers concerning the Penmachno charity founded by Roderick Lloyd of Bennarth in that parish; rentals of the Ystumcolwyn estate, 1717-1791. Members of the William(e)s family represented in the papers include Lumley Williams, John Williams (and Meriel his wife), Lumley Williams II, Lumley Williams III, Meriel Williams III (daughter of Lumley Williams III and wife of Arthur Williams III of Meillionydd) and Edward Williams.
There is also a group of additional manuscripts that were deposited in 1965 and 1966, which consist mainly of deeds and other documents relating to the parishes of Brithdir and Islaw'r-dref, Cae'rdeon and Bont-ddu, Corwen, Cymmer, Dolgellau, Garthgynfor, Gwyddelwern, Llanaber, Llandanwg, Llanegryn, Llanelltud, Llanfachreth, Llanfair, Llanfihangel-y-Pennant, Llanfihangel-y-traethau, Llangelynnin, Llanuwchllyn, Llanymawddwy, Mallwyd, Pennal, Pentre, Tal-y-llyn, Trawsfynydd, Tywyn, co. Merioneth; Guilsfield, Llanfyllin, co. Montgomeryshire.