Looking for William Withernwick and Elizabeth Withernwick in the 1851 Census- Beverley - Hull area. (they would both be 40-41 yrs old in 51) I believe her maiden name was likely Scott. In 1854 they left the port of Hull coming to Canada with a Stephenson (Stevenson) family, that they were related too. In 1851 the Stephensons are found in Stoneferry, Sutton Parish (Hull area), but I'm not sure about the Withernwicks??
The Scotts were I believe from Cottingham, with all the Stephenson children being baptised there.