Where to buy replacement gas fire radiants?

We have a gas fire, which is now in need of 2 new radiants.
On the rear of the radiant moulding it states -

Type SX12
T & N
G.C.No 135-868

Above the fire control, it is labelled "Radiation".
Apart from that I can't identify the Make/Model.
Can anyone advise where I can buy replacement gas fire radiants?