Edmund Mortimer
... that during the exile of Roger Mortimer, 1st Earl of March, his eldest son Edmund Mortimer was imprisoned at Windsor Castle?
... that during the exile of <a href="./Roger_Mortimer,_1st_Earl_of_March" id="mwBaY" rel="mw:WikiLink" title="Roger Mortimer, 1st Earl of March">Roger Mortimer, 1st Earl of March</a>, his eldest son <b id="mwBac"><a class="mw-redirect" href="./Edmund_Mortimer_(1302–1331)" id="mwBag" rel="mw:WikiLink" title="Edmund Mortimer (1302–1331)">Edmund Mortimer</a></b> was imprisoned at <a href="./Windsor_Castle" id="mwBak" rel="mw:WikiLink" title="Windsor Castle">Windsor Castle</a>?