Quite a well known folk song, even around the Oz folk clubs!!
The lyrics tend to support the notion that 'poverty knock' is indeed onomatopoeic


http://www.yorkshirefolksong.net/song_database/Occupational/Poverty_Knocks.40.aspx

You can hear it here!

http://www.youtube.com/watch?v=Blw5_H9aw-U

My Gt-grandfather and grandfather worked at Clough`s as Finisher`s.Also, a Mender in the family . Lady near where I live was a Doffer.
One old lady I knew spent her whole life from being an half-timer in the mill as a weaver spent the last 2 years of her life in a N.H. Had to sell her house to pay her fees and died penniless after a life-time of scrimping and saving and hard work!

Years at KBGS e.g. 1958-1964 (optional) `59-`66

Current location (optional) HAWORTH

So, what was a doffer?

Years at KBGS e.g. 1958-1964 (optional) 1958-65

Current location (optional) Leeds

a doffer was the person who went around the weaving shed from loom to loom collecting the empty bobbins. He wheeled a box to allow him to collect quite a number. The bobbins were then sent back for refilling.

Years at KBGS e.g. 1958-1964 (optional) 1949-53

Current location (optional) Bingley

Hi Shaun -

Poverty knocker is almost certainly a (grimly)
humorous name for a weaver.
Old Tommy Daniels of Batley used to sing (and might
have written)the song Poverty Knock which has the lines:

Poverty, poverty knock,
My loom it is saying all day,

The reference is to the sound made by the shuttle and the
poverty of the hand loom weavers.
Clearly the term lived on well into the time of the power loom.

I've just checked Wright's English Dialect Dictionary and it has
Poverty knocker - a. a weaver; b. the shuttle of a hand loom.

Years at KBGS e.g. 1958-1964 (optional) 1958-64

Current location (optional) Haworth

These two films migh be of interest:

http://www.youtube.com/watch?v=WohhLX_YLlE

about life in the West Riding in 1945

but, of more relevance is:

WIMSOL BLEACH FACTORY, KEIGHLEY (1951)

http://yorkshirefilmarchive.com/film/wimsol-bleach-factory-keighley?destination=search%2Fapachesolr_search%2Fkeighley%3Ffilters%3Dtype%253Ayfa_film%26highlight%3Dkeighley%26mode%3Dquick%26solrsort%3Dscore%2520desc%252C%2520sis_cck_field_film_id%2520asc&highlight=keighley

from 'The Yorkshire Film Archive'

Years at KBGS e.g. 1958-1964 (optional) 1959 - 1966

Current location (optional) Lancing/Shoreham border

Both videos posted before in the thread "We of the West Riding (in 1945)"