There is a version of this on an LP by "the City Waites" who point out that the original version had the chorus in the form

Lavender's green, Lavender's blue
You must love me 'cos I love you

Has anyone any idea when the colours swapped round? (They unfortunately didn't give a precise source and date for this in the sleeve notes, but everything else on the LP is 15c - 17c . They also say they left out 23 of the original verses)