Brooks did make vinyl saddles, and it is possible yours in an original. From what I see on line, the Deluxe version of the Raleigh Sports had Brooks leather saddles. The Standard version most likely came with the vinyl saddle as a cost reduction. I have a Raleigh Sprite that has a Brooks vinyl saddle as can be seen here:
http://www.flickr.com/photos/stl914/...7622653476718/
Follow this link to see if your saddle is among those pictured:
https://www.google.com/search?q=broo...bih=589#imgdii=_