"Bonny Wood Green" is a ballad from World War I, still sung in Irish pubs today. The Irish were unenthusiastic about entering the war on the British side, but once the decision had been made there were surprisingly large numbers of volunteers. The divided loyalties of the Irish soldiers cannot have made their ordeal in the trenches any easier.
In Celtic music, the dotted rhythms are often treated with a lot of snap. In this case, the dotted rhythms, while preserving their lilt, should be smoothed over a little, the way pebbles are rounded by the sea.
Irish balladeers frequently keep time with foot taps or by tapping their hands against their legs. It would be effective if the singers also kept gentle time with their hands against the sides of their legs, marking the dotted quarter pulse. An understated sway would also be , effective, provided the motion arises from the singers' own inner sense of rhythm. Any swaying movement should be in the interest of the singers feeling the lilt, not in showing the audience that the choir is having a good time.