We did that one in assembly where you sing 'And everyman 'neath his vine and fig tree, shall live in peace and unafraid'. You'd sing that, then when you sung the second line, a second group started singing the first line. And when you got to the third, there'd be two groups also singing lines 1 and 2. It went on for hours and was one of the most musically satisfying things ever.
'Autumn Days' was good too. As was 'Jerusalem' at the end of term school gathering.
I fucking hated 'Morning has broken' mind.