very similar to the version Ewan MacColl recorded - though my memory is that Ewan had 43 verses? There were more verses about how the boy got to the castle ... I remember for instance
ye maun rin for me Willie ye maun rin re speed/pride
when ither boys rin at their feet on horseback ye maun ride

[he couldn't ride over the river as the bridge was down]

when he cam tae the broken brig he bent his bow and swam
when he cam tae the other side, took up his feet and ran

I daresay that version is on mudcat somewhere; I'm just saying the versions here are not so different. I would love to see or even read the play that was based on the ballad. And I always liked the baron's remorse when he learned that Gil Morice was actually his lady's son (not that I would agree with murdering a wife's lover)