Little Musgrave And The Lady Barnard (Child # 81) has been collected in Scotland, England, Canada & the US, as far as what I've seen it hasn't been in the Irish tradition and Child refused to collect the Irish ballads because he felt inadequate and tried in vain to encourage others to do so. The oldest English copy dates to 1658 although a stanza is quoted in Knight Of The Burning Pestle, 1611. In versions the Lady is butchered "He cut her paps fromoff her breast great pity it was to see that some drops of this ladie's heart's blood ran trickling down her knee" and some have her pregnant "I'm not sae wae for my lady for she lies cauld and dead but I'm right wae for my young son lies sprawling in her blood" and sometimes remorseful and blameless asking why someone didn't stay his hand when he slew the 'bravest fair knight' and the 'fairest lady'.