Pancake air filter

[Gareth]

Hi, does anybody know where I can get a replacement paper air filter for the pancake air filter fitted to the HS6, 1 3/4" SU carb on the Roadster. The sponge filter in the new pancake filter I bought measures about 13.5 od, 12 id, and 2.5 cm high, and seems to be letting far too much air through! It's noisy and runs like a pig!
I can get endless pancake filters fitted with sponge filters, but buggered if I can find a paper one!
Cheers Gareth.