|SOME NOTES ON MEDIEVAL ENGLISH GENEALOGY|
Volume 9, page 143:
He [Thomas de Monthermer (d.1340)] m. Margaret, probably the widow of Henry TEYES [LORD TEYES], who was executed in 1321.(l) ... She d. 15, 22 or 26 May 1349.(m)
She held in dower 1/3 of the manor of Lydiard Tregoz, Wilts, which belonged to the said Henry (Cal. Close Rolls, 1343-46, p.50; Cal. Fine Rolls, vol.iii, p.427; Cal. Inq. p. m., vol.vi, no.535).
[Cal. Inq. p.m.,] vol.ix, no.344.
Thomas was married to Margaret by 1330, when part of the manor of Lydiard Tregoze was held by Thomas de Monthermer [Victoria County History, Wiltshire, vol.9, p.83, citing P.R.O. CP40/283/229].
As well as the evidence from the tenure of Lydiard Tregoze, it was recorded in 1428 that Margaret de Monte Hermery had formerly held half a fee in Bockhampton [West Bockhampton, in the parish of Lambourn], Berkshire [Feudal Aids, vol.1, p.62]. In 1324 the king had ordered a messuage and land in Bockhampton to be delivered to Margaret, late the wife of Henry Tyeys, which had previously been granted by fine to Henry and Margaret for their lives [Cal. Close Rolls, 1323-27, pp.122-23].
This identification of Margaret is supported by a comparison of the date of death - 20 May 1349 - given for Margaret the widow of Henry Tyeys at Alice de Insula's inquisition post mortem [Cal. Inq. p.m., vol.9, no.571; cf. Cal. Fine Rolls, vol.6, p.277], with the dates of death given for Margaret the widow of Thomas de Monthermer at her own inquisitions post mortem - 15, 22 or 26 May 1349 [Cal. Inq. p.m., vol.9, no.344].
Explicit confirmation of the identification is provided by the record of a plea concerning property in Lydiard Tregoze in Easter Term 1342, in which Margaret, who was the wife of Thomas de Monte Hermerij, said that she held the property in dower of Henry Tyeys, formerly her husband, of the assignment of his sister and heir, Alice [CP 40/330, m. 82; see image at AALT].
[Douglas Richardson pointed out the additional evidence about the tenure of Bockhampton in January 2002, and the entry in the plea roll of 1342 in June 2016.]