One last bit of info. 
At the Annual Licensing day in Rochester, Kent, in 1850 the Railway Tavern was in the process of being built.
At the next Annual Licensing day, Sat August 30th 1851, James Prudhoe's licensing application was refused.
From "The Era" London, Sept 7, 1851.
"... The Town Clerk (Mr Lewis) on behalf of Mr James Prudhoe, formerly Inspector of Works on the North Kent Railway, and now Beer Retailer, applied for a License for the Railway Tavern, a newly erected house, the property of Sir Henry Meux and Co. ....."
Main opposition was from the landlord of the Canal Tavern a short distance away.
"The Magistrates having consulted. The Mayor said the application was refused."
Might have been enough to drive him back to his previous employment.
Alan.