Britain's Royal Families: The Complete Genealogy by Alison Weir

Paris. Margaret was never crowned. She died on 14 February, 1317/18, at Marlborough Castle, Wiltshire, and was buried in Greyfriars Church, Newgate, London. Her tomb was lost during the Reformation.
    Issue of marriage:
    1   Thomas
    He was born on 1 June, 1300, at Brotherton, Yorkshire, and was created Earl of Norfolk on 16 December, 1312. He died between 4 August and 20 September, 1338, and was buried in the Abbey of Bury St Edmunds, Suffolk.
    Thomas married firstly, between c. 1316 and 1320 (although no evidenceexists as to where):
    Alice
    She was the daughter of Sir Roger Halys or Hales of Harwich, Essex. She died after 8 May, 1326, and before 1330.
    Issue of marriage:

(i)
Edward
He was born in c .1319/20, and died before 13 September, 1337, perhaps in 1332 (?).
Edward married, in May/June, 1328 (although no evidence exists as to where):
Beatrice
She was the daughter of Roger Mortimer, Earl of March, by Joan, daughter of Peter de Genville. After the death of Edward, she married secondly Thomas de Braose, Lord Brewes, in c. 1334 (before 13 September, 1337), and had issue:
1  Beatrice; she married William de Say, Baron Say (1340–1375), and had issue.
2  John, a knight ( d. 1367); he married Elizabeth de Montacute.
3  Thomas, a knight ( d. 1395).
4  Peter.
5  Elizabeth.
6  Joan.
Beatrice died on 16 October, 1383.
(ii)
Margaret
Known as ‘Margaret Marshal’, as the Dukes of Norfolk have always held the office of Earl Marshal of England, she was born around 1320/22. She married firstly John de Segrave, 4th Baron de Segrave (1306 or 1315–1353), after 3 March, 1327, and probably in 1337/8, and had issue:
1  Elizabeth (1338–1375/6); she married John, 4th Baron Mowbray of Axholme, Lincs. (1340–killed 1368), and had issue.
2  Anne, Abbess of Barking ( d.c. 1377).
Margaret succeeded her father as Countess of Norfolk between August and 20 September, 1338. She married secondly Walter, 1st Baron de Mauny or Manny ( d. 1372), before 30 May, 1354, and had issue:
3  Thomas (drowned in infancy before 1371/2).
4  Anne (1354–1384); she married John Hastings, 2nd Earl of Pembroke (1347–1375), who had married previously Margaret, daughter of Edward III, and had issue.
Margaret was created Duchess of Norfolk for life on 29 September, 1397. She died on 24 March, 1399/1400, and was buried either in the Charterhouse, London, or in Greyfriars Church, Newgate, London.
(iii)
Alice
She was born in c. 1324. She married Edward de Montacute,1st Baron Montacute ( c .1304–1361), before 16 January, 1339, and possibly before 29 August, 1338, and had issue:
1  Elizabeth ( b .1344): she married either Walter de Ufford or Sir John de Braose ( d .1367)
2  Margaret ( c .1347–before 1351/2).
3  Joan (1349–1375); she married William de Ufford, 2nd Earl of Suffolk (1339?–1382), and had issue.
4  Matilda ( c. 1350–1394); a nun, later Abbess of Barking.
Alice died probably between 14 November, 1351, and 30 January, 1352 (certainly before 16 November, 1361), at Bungay, Suffolk, of wounds received as a result of an assault by her husband.
    Thomas married secondly, in c .1328 (although no evidence exists as to where):
    Mary
    She was the daughter of Peter de Braose, and married firstly Ralph, Baron Cobham of Norfolk ( d .1326), by whom she had issue:
    1 John (1324–after 1378), Baron Cobham.
    Mary died on 9 June, 1362 (or between 17 April, 1361, and 20 June, 1362).
    Issue of marriage:
       (i)    John
    No dates are recorded. He was a monk at Ely Abbey, Cambs.
    2  Edmund
    He was born on 5 August, 1301, at Woodstock Palace, Oxon., and was created Earl of Kent on 28 July, 1321. He was probably styled Earl of Arundel as well, as he held the castle and honour of Arundel, but he was never formally so created. He was executed for supporting his brother, the deposed Edward II, by order of the Regents Mortimer and Queen Isabella, on 19 March, 1330, outside Winchester Castle, and he was buried in the Church of the Dominican