The EDP (local Norfolk paper) has been running an offer called Delicious Dining - Dine for Half Price.
The original offer was that you could purchase £50 vouchers for £25 - but this has now been reduced to £15 (+ £1.50 P&P)
Further great news - the voucher is for any time (not restricted to Mon - Weds etc but obviously subject to booking) and for any menu (no restrictions).
It also includes drinks. This is ideal for a couple looking for a cheap night out.
I have eaten at one of the places (The Olive Garden) and the food was excellent.