The estate originally comprised property p's Llanynys (t's Maesmaencymro, Gyffeilliog), Llanfwrog (t. Bodangharad), Ruthin, Llanbedr Dyffryn Clwyd, Bodfari (t. Aberchwiler), Llandyrnog, Llanhychan, Llangwm in commote of Dinmael, the lordship of Llwynydd and Rhisgog, all in co. Denb. In 1697, property in p's Derwen, Llanelidan and Llanfair Dyffryn Clwyd, co. Denb., and p. Llandrillo-yn-Edeirnion (t's Garthiaen, Branas Isaf), co. Mer., is added. In 1701, property in p's Penmorfa, Beddgelert, Dolwyddelan, Capel Curig, Penmachno, Llanberis, Dwygyfylchi and Llanfairfechan, co. Caern., is also added. Sir William Williams bought the Glantant estate in 1679, and it appears in the Glascoed collection in 1680. The Plas-y-ward estate is combined with the Glascoed collection, 1704-1715 (R12-R13). From 1712 (R13) property in p. Llanynys (t's Trefechan, Ysgeibion) and [p. Llanrhaeadr-yng-Nghinmeirch] (t. Pentrellech) is added. RA8 (1653) contains property in p. Oswestry (t's Trefonnen, Treflach), Shropshire. R4/8 contains an inventory of the goods and chattels of Edward Thelwall of Plasyward, co. Denb., esq., appraised in Jan. 1677. Collector: Matthew Jones, 1689 [1715?].