NOTES ON SURNAMES (HULL) 28
HINCH Perhaps the same as Hince, and so from the place name Hints, of which there are two; Hints near Coreley in Shropshire, and Hints, Staffordshire. Ekwall (“English Place Names”), who refers to the former only, suggests that the name comes from the Welsh hynt ‘road’, with an English plural S. Hince appears to be best represented in the Anglo-Welsh border counties. Hinch, on the other hand, is strongest in the East Midlands, and well represented in Lincolnshire, from the early 18th century in my records. The name appears in Hull from the 1870s.
It is also possible, I suppose, that Hinch is a variant of Inch, which, rightly or wrongly, I think of as a Scottish surname. Inch would be from the Gaelic Inis, “island”.