There is evidence of a triangle decal on my bike, at that location. And I noted there was one there on this ebay bike, which is much like yours:
completed auction:
http://cgi.ebay.com/1973-Raleigh-Pro...item2a0b21e739
I found them for sale here:
http://www.hlloydcycles.com/
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1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"