Nice looking roadster. Have you tried http://www.transport-museum.com/ ? I emailed them recently and they were very helpful and past on some great contacts. One being a 75 year old gent in Coventry called Dave Mac - tel (024) 7668 3239. He has been making and repairing Rudge Whitworth bike parts (mainly motorbikes) although he has a few push bikes. I bet you he could tell you a nugget or two about Swift. I'd be interested to see some better pictures of your bike as I have a 1939 Rudge Whitworth. Probably a few similarities. I'm having a mare putting this back on http://www.bikeforums.net/showthread.php?t=357385
Good luck with it.
Pit Canary