When Raleigh Team Pro's were introduced in 1974, they came with shift-lever bosses brazed onto the downtube in position to be used as bottle-cage bosses. I am guessing that if bottle-cage bosses had been widely available at the time, these top-end bikes would have come with real bosses, rather than this weird looking kluge.
I think that a custom frame builder could easily just get some flat pieces of metal, drill them, braze them on the downtube, and tap them out. So, an exact date for "who did this first" may never be known...
- Don Gillies
San Diego, CA, USA