Thank you all sooo much! but none of those are the version I sing (which I learnt from an Irish singer I know). The version you have mostly given me is the one sung by Joan Baez, which I also know. But I prefer this other one. I don't read music well, but I've just played the first line on my recorder, which goes like this:

b b e g g f(sharp) ga f g
Black is the colour of my true love's hair