I thought I remembered some other messages in this thread!

I have on Martin Carthy's The Collection. I also have the music for the psalm tune Otford in The Singing Seat transcription by Edwin Macadam and Tony Singleton, c1995. It's Common Meter , ie 8686, but Carthy makes it fit by dropping the very, very's, other words here & there and putting 2 syllables on 1 note in a number of places. He gets 8 lines out of 4 lines of music by doubling both sections of the music - aabb instead of ab.

The version Carthy used was 3 parts, while this one is 4 but the tune & the fuge are basically the same. It must have been popular in it's day as a psalm tune as there was a printed version in 1746, Carthy's was a hand copy from ca1813, & the Singing Seat version is from a hand copy 1830's. Cool use of a psalm tune.

Here's my reading of the questioned verse & a few more words with a line break to correct the next.

We're low - we're low - we're rabble, we know
Yet, at our plastic pow'r,
The mould at the lording's feet will grow
Into palace and church and tower
Then prostrate fall - in the rich man's hall,
Cringe at the rich man's door;
We're not too low to build the wall,
Too low to tread the floor.

We're low we're low we are so low
Yet from our fingers glide
The silken flow and the robes that glow
Round the limbs of the sons of pride
And what we get and what we give
We know and we know our share
We're not too low the cloth to weave
Too low the cloth to wear