Hi all, Genuine, proper Dowty ” AIR/OIL hydrolic Forks were NOT fitted to Birmingham Scotts, (except for a few early proto types which were) They were fitted to Velocette, Panther, Scott, and other less well known makes. Brum” s look very similar but the legs totally different. Only the yolkes and top outer tubes are the same. As Stan notes Brum fork springs stretch, not compress as do all others makes I have seen. Dowty Air/oil forks CAN be converted to springs, and many were, but Brum forks are not converted Dowty air/oil forks. I dismantled, measured, and compared both types for an article for YOWL some years ago ,read for the full saga! Geoff.