UNKNOWN ! Please HELP me identify this Vintage frame !

I got this at a swap meet basically for it’s parts. Upon disassembly, things about it seemed odd to the point of maybe I had stumbled onto something worth saving. Frame is light for it’s size. The T/A crank has odd sized extraction thread size. Derails and clamped to downtube shifters are Suntour. Lugs are kinda neat, has had a pair of horizontal rivets securing the missing headbadge. Paint looks original, (or a long ago and fairly detailed respray),yet there is evidence it started out as kind of a robin egg blue. Only stamping I’ve found is “C.28” on the bb shell. I’m thinking a Raleigh of some sort but really have no idea. Maybe someone here can solve this mystery. One other thing, the front derailleur attaches to a seemingly crimped onto tube mounting ring.
wedgeSG