I'm surprised nobody has picked up on this. Textile Mills? Milling what? Probably cotton? Picked by who? Slaves.
Picked by slaves in the USA yes, but how was this of any advantage to cotton mill labourers in the UK? Also the USA was out of British control by then. Textile manufacture in the UK was not just cotton. Wool and flax were also big industries. Some of the largest industrial mills in the textile districts were wool/worsted.
Everyone in Britain benefit from the wealth that flowed into the country because of slavery and the industries that depended on slavery.
Which industries apart form cotton depended on slavery. Unless you mean the unregulated labour of British people, including children, in industries like coal, where the death rates were extremely high.
Read North and South by Elizabeth Gaskill,
I already have
people moved to the mills from the countryside chasing the money, millwork was better paid than the rural alternatives.
People moved into the factory towns and cities because their labour in the fields had been replaced by agricultural machinery and because their cottage industry and wages, hand loom weaving for example, had been undercut by the factory system.
Industrialisation did not improve these peoplrs lives. In some cities it greatly reduced life expectancy. A wool comber living in an overcrowded city slum in the north of England had a life expectancy of about 14 years.
Cotton was not the only industry and industrialisation, including textile manufacture, would have happened without it.
Coal was the big game changing industry. Britain, or even just England alone, was the largest exporter of coal in the world before WW1.