Rodger de Mortimer, Lord Wigmore - Knights of the Garter

You are probably correct about the picture, this Roger de Mortimer, Lord Wigmores Birth: circa 1155 Wigmore, Herefordshire, England
Death: before August 1214 Wigmore, Herefordshire, England.
https://en.wikipedia.org/wiki/Roger_Mortimer_of_Wigmore

So most likely a common ancestor and following the family tree it appears he is a Great Grandfather of the 2nd Earl of March.