Italy to Manchester before 1820

[Wiganexile]

My Barlow ancestors are said to have come from Italy, and my grandmother and her nephews certainly looked italian.  It has been suggested that their name was originally Barlotti. 

I have traced the family back as far as William Barlow, born in Salford in or about 1820, son of John Barlow.

If the family is italian, what might have taken them to the Manchester area at the turn of the 19th century?