Quoted at Henry's Songbook:

[1992:] I know that Dave Goulder was insistent that people should sing January Man the way he wrote it - "If I had wanted people to sing 'smiles at each newcomer', I'd have written that instead of 'grins at each newcomer'." (Imlach, Reminiscences 167)

I don't know if that's definitive; I seem to recall that Martin Carthy changed the song a bit, but not in what way. You can probably still get copies of Daves's songbook, January Man, if you look around a bit.