Joe has beaten me to it with me own link. The ref to Villikins tune in the dated post concerns the "Soldier and Sailor" series, not the mare and foal. I had the mare and the foal from another singer way back in the sixties, and I seem to remember the late John Rennard being the source. Beyond that, regrettably, not much detail. I have no idea if a recording exists, but can certainly supply the dots as I'm still singing it. Thanks Joe also for the Moeran reference.