It is an Andy M. Stewart song, if I am not mistaken, too too overly popular in US, maybe written for the US market, as you say about the colors, in my estimation, not his best, but I hate 'Take her in your arms' as well, even though it is in the traditional style! How we Americans (some of us, anyway) do giggle & blush over the mere idea of such natural things! & British girls know full well what is under there, that's why they don't have to look! I keep waiting to hear about the young Prince having to present identification in some American bar when someone would ask, 'oh yeah? Show us you're Willie!'