I may owe Norwich an apology based on their link:
http://www.norwichairport.co.uk/documents/NorwichAirportFees&Charges_Apr07.pdf
My reading of this is that a GA (i.e. non-transport) flight will only attract the stated landing fee, less 25% for prompt payment. If this is true then I stand corrected, however a real pity the guy in the ramp office gave me a bum steer!
Mike