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lug pattern appears to be Prugnat F4
pattern launch May 1976
would think frame dates from shortly thereafter...
unable to see anything suggestive of Ernie Clements heritage
joinery of taper tube ends may twig the memory of a reader; stays are simple domed design while blades exhibit the "chisel" style. "usually" a builder will follow the same pattern front and rear...
shell appears it may be BOCAMA although NERVEX also offered a pattern nearly identical to the BOCAMA one...
regarding top tube guides -
these simple rings/ferrules are more commonly encountered when used a housing guides on the chainstay or as guides for fingertip cables. frame appears to have been done just as top tube cable housing guides were beginning to come into fashion. perhaps customer requested them but builder had no purpose-made top tube guides on hand so put these to work in this spot out of convenience.
national origin -
appears to me we are in the anglophone world here. the domed stay ends would
tend to be contraindicative of a U.S. origin. used widely in Britain. however, the Campag Nr. 621 chainstay stop is sending the opposite message. while common for Brit builders to employ the Campag bb cable guides they "usually" use something other than the 621 for a chainstay stop. the 621 was used widely by yank makers.
curbtender -
one exploration you could undertake would be the shell interior to examine the extent of tube mitre done and the presence or absence of pinning.
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