The mills in Boston plus other areas needed skilled workers and many from the mill areas in England were recruited to go and work there.
Your ancestor was a mill foreman could it be he went there to
help set up production at a new mill, I expect many of his fellow passengers were mill workers.
Unfortunately the 1890 census was destroyed I had hoped to find them in Boston.
Francis Harker was back in England ref: 1901 census age 52, wife Marjory 48, Alexander 19