Good find, DD; that's a remarkably comprehensive site. I know the area quite well. Although it's on the South Staffordshire coalfield, nobody thinks of it as anything other than the Black Country.
It's clear from the pictures that the major development was in the Victorian age, as was Birkenhead. Darlaston, however, is considerably older; just to use the figures from the 1801 census, Darlaston: 3812 inhabitants, Birkenhead: 110 inhabitants. (Actually, at the time, Tranmere was bigger than Birkenhead, with 353 inhabitants).
Because of the presence of both coal and iron ore, there was a lot of smelting and heavy industry in the area. When I knew it, in the 1960/70's it was a miserable and dirty place.