Im in manchester,1 hour drive(ish)from leeds on the M62 motorway. This sort of had me thinking why just midland industry? Trafford park(manchester) sprung immediately to mind, bombed in the ww2, an industrial hotbed in the NW england. Oldham slightly closer to leeds than manchester full of mills, midlands to me is the car industry or pottery(stoke on trent)
Staying in leeds i would search for yorkshire industry, right now nothing springs to mind other than the mills and the leeds liverpool canal. Todmorden, Hebden bridge those 2 places do have plenty of industrial heritage.
When are you going to leeds? Give us a few days and see if i can help more