Ancestry Family Trees. (Online publication - Provo, UT, USA: The Generations Network. Original data: Family Tree files submitted by Ancestry members.) Ancestry Family Trees.
"By his marriage with Joan, sister and coheir of Thomas son of Robert de Alfreton, [Robert de Lathom] became possessed of a moiety of her father's estates in Alfreton, Norton, and Marnham, held of the honour of Tickhill. She probably died without issue, as these manors did not remain with the Lathom family."