"They hae slain the Earl o' Murray/And laid him on the green."

Ms Wright heard this as a child as "They hae slain the Earl o' Murray/And Lady Mondegreen,"

There's got to be a special name for a mishearing like this that results in what would be an eponym if it weren't a mishearing. I think mondegreen should be reserved for this meaning and something else be used for ordinary mishearings like "Scuse me while I kiss this guy".