Just found this deal at Robert Dyas. Exitex Radiator Heat Reflector Foil was £9.99 reduced to £3. Exitex Radiator Heat Reflector Foil
A simple, cost-effective way to get the most from your central heating, this foil sheet is designed to reflect heat back into your room. It's easy to fit, with enough foil for three standard radiators.
Reduces heat loss by up to 35%
Enough for 3 standard radiators (0.5 x 5m)
Fitting instructions included
Hope this deal helps someone.