William was the son of sir Marmaduke de Thweng and Agnes de Northwood. The date and place of his birth have not been found.
sir Marmaduke de Thweng |
Edmund de Thweng |
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Isabel Constable |
Robert Constable |
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Katherine de Mauley |
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Agnes de Northwood |
sir John de Northwode |
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Agnès de Grandson |
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