MOSTYN, William (by 1518-76), of Mostyn, Flints. and Gloddaeth, Caern.

Published in The History of Parliament: the House of Commons 1558-1603, ed. P.W. Hasler, 1981
Available from Boydell and Brewer



Apr. 1554
Nov. 1554

Family and Education

b. by 1518, 1st s. of Thomas Mostyn of Mostyn and Gloddaeth by Jane (or Siân), da. of Sir William Gruffydd of Penrhyn, Caern. m. (1) by 1543, Margaret, da. of Robert ap Hywel of Whittington, Salop, 3s. inc. Thomas 2da.; (2) Margaret, da. of Sir William Brereton of Brereton, Cheshire. suc. fa. 1558.

Offices Held

J.p. Flints., sheriff 1560-1, 1565-6, 1570-1, Caern. 1567-8; commr. piracy, Flints. 1565, militia 1570, victuals 1574, tanneries 1574.2


The Mostyns were among the most ancient and influential of Welsh families, related by blood to Owain Glyn Dwr and also to the Tudors, whom they consistently supported, in arms and otherwise, both before and after they succeeded to the throne. They were also great patrons and collectors. The manuscript library of Welsh literature they built up over the ages remains one of the basic collections in that field. Originating in Denbighshire, they had in the course of the middle ages acquired through fortunate marriages wide estates in three other counties. One of these, the manor house and lands of Mostyn in Flintshire, became the principal seat of the family from the time of William Mostyn’s great-grandfather, and from the next generation the name of the seat was adopted as a family surname. In 1570 William Mostyn began extensive additions to the house.

Mostyn served Queen Mary against Wyatt’s rebel forces in January 1554, and represented Flintshire in both the Parliaments of that year. Thereafter he did not sit again until 1572, and it was in the course of this Parliament that he died, 19 Sept. 1576, lamented by bards of Denbighshire, Flintshire and Caernarvonshire, ‘hand and eyelid for the whole of Wales, and a strong hand in England’. His will, dated 20 Feb. 1566, and proved 17 Nov. 1576, named his ‘well-beloved wife’ executrix.3 He was succeeded in the representation of Flintshire by his son Thomas.

William Mostyn the elder, the subject of this biography, is sometimes confused with two relatives and namesakes: his own younger brother (usually referred to as William Mostyn the younger), and his cousin of Basingwerk and Cornish, Holywell, son of the founder of the Talacre branch of the family.

Ref Volumes: 1558-1603

Author: A.H.D.


Except where otherwise stated, this biography is based upon L. N. V. Lloyd-Mostyn and T. A. Glenn, Mostyns of Mostyn.

  • 1. Did not serve for the full duration of the Parliament.
  • 2. CPR, 1563-6, p. 36; APC, vii. 286; HMC Welsh, i. 291-5; Flenley, Cal. Reg. Council, Marches of Wales, 60, 69, 109.
  • 3. PCC 37 Carew.