The contractual requirement to stop at Berney Arms goes back to 1860 but I would imagine that the agreement is no longer in operation!
The answer is that like a number of our remote stations, it was part of a deal with the landowner to allow the railway to pass through their property. The more southerly of the two lines from Norwich to Great Yarmouth, it opened in May 1844, gaining the distinction of being the first railway in Norfolk. Thomas Trench Berney had sold the land to the Great Eastern Railway but few passengers used Berney Arms Halt, which they’d built to honour the agreement. Then the company realised that the deal was for a station and not for trains to actually call there, so they stopped serving the halt. A legal battle ensued which the company must have expected to lose, as in 1855 they started stopping trains here again, although the court didn’t issue its findings until 1860. Agreement was then reached for one train each way to stop on Mondays, Wednesdays and Saturdays and for Mr Berney to be paid £200 in compensation, a not inconsiderable sum in those days.