Early life and family
She was born Margery Burnham or Brunham around 1373 in
Bishop's Lynn (now King's Lynn),
Norfolk, England. Her father,
John Brunham, was a merchant in Lynn, mayor of the town and Member of Parliament. His mercantile fortunes may have been negatively affected by downturns in the economy of the 1390s (especially in the
wool trade), although he was clearly a successful politician. The first record of her Brunham family is a mention of her grandfather, Ralph de Brunham in 1320 in the Red Register of Lynn. By 1340 he had joined the Parliament of Lynn.
 Margery’s kinsman, possibly brother,
Robert Brunham, became a Member of Parliament for
Lynn in 1402 and 1417.