I must apologize to Bram thinking i had a Matchy Girder spring. It turns out it is for a Matchy or AJS lightweight forks which is 9 inches long.When i measured mine it was in the bike at 9 inches but that was compressed. The true uncompressed length should be 10 3/4 inches with 18 coils. The Yahoo group provided me with this information.

British Only Austria have a spring for sale claiming to be M20 but looks like an 18 coil webb spring to me. Can anyone here verify for Bram what it is?