Alasdair Clayre's song as he did and as done by Gordon Bok have a few variations. What follows is the way I play it, The chords are based on Clayre's melody and not Boks bass heavy notation. I think how ever you choose to sing it really OK. The little lyric variables are folk process and just fine.
A Gentle Easy Flowing River capo at 4 sounds in “B”
(G) (D) G C G
When you come afloat In the morning light
C D C D
And you're towing through the summer weather
C D C D
And you use no clock but the ebb and flood-line
Em C D G
It's a gentle easy flowing river
But when you're out on deck in the big spring gales GCG
And you hunch aboard your barge and shiver CDCD
You go creeping slow against the weight of water CDCD
With the ebb tide pushing down the river Em C DG
And it's cold on board in the winter dark GCG
And you think the night will last for ever CDCD
And you crouch and wait there below in your cabin CDCD
As the dawn tide takes you own the river Em C DG
And you've stood out there in the lightning storm GCG
As the big wave punch the boats together CDCD
And the thunder shakes the steel below you CDCD
As you're working on the open river Em C DG
Well it ebbs and flows with its rain and oil GCG
When London's gone it will flow on forever CDCD
To the sea and its grime and its black salt water CDCD
It's a gentle easy flowing river. Em C DG