For probably about 20 years or so before his retirement in 1981 my father was a nigh shift works manager for a company that made rubber mouldings and rubber to metal bonded bushes, it was a dirty and as you have said, boring and repetitive job, less so for my father as the boss though.
It was however relatively well paid for manual work as it carried the night shift premium, it appealed to the real grafters who did not mind getting their hands dirty to be well rewarded, many of them had second daytime jobs like running a corner shop or market trading.
Throughout the whole time he never had more than 3 white people working for him and even they were Canadians/Australians etc, the English generally didnt like the work and the conditions and werent prepared to make a sacrifice even for short term gain like the immigrants or ex-pats (or should that be colonials?).
The rest of the night shift, some 50 or so were a mixture of Indians, Pakistanis, Bangladeshis and Ugandan Asians,my father sometimes had his work cut out with fighting between the various religions, by far the most loyal and hard working were the Sikhs, they pretty much all were shopkeepers, some still work in the shops with their descendants despite being in their 80's now, I think pretty much all of their kids are now successfull businessman judging by those that I am still in touch with.
That is not to say there werent the opportunists amongst them (I wont say what race or religion) but they were the ones that would be clocking in to more than one factory, working whilst also claiming social security, generally doing their best to avoid work whilst being paid, sleeping on the job, taking the maximum time off sick and calling in the race relations board when disciplined.
We moan at the loss of ,our industries to China but I reckon the current generation would be even less wiling to do these jobs if they were still available in Europe