Duncan Granger stated and then asked:
<< I recently acquired a 1973 Jack Taylor Tour of Britain (#6559) that has Campy vertical rear dropouts. They are clearly original. I've learned from the archives that campy introduced them some time in the 60s. Also that Raleigh used them on the R.R.A. in 1973 (same year as my JT). So, questions: Why vertical rear dropouts in 1973? Did they have some special advantage that made them better for a specific discipline (i.e. TT)? Why did they take so long to catch on?>>
Several years back, I bought a used Woodrup frame (sight unseen - wasn't I the brave one!) which arrived with vertical dropouts and brazed-on stops where one might expect to find shifter bosses. I was interested in perhaps having it refinished (I didn't like the color all that much) and called Peter Weigle to discuss some points. When the subject of vertical dropouts came up, Peter informed me that they were the preferred dropouts for touring frames as they were stronger than horizontals and made wheel changes, and therefore tire repairs, easier.
Concerning the 1973 RRA: I've had three of these (one I bought new in 1973) and I suspect it was more of a small cost factor as well as a "different" factor for Raleigh. The RRA was introduced and not intended to compete with the Pro, so parts were the less expensive French variety, and since the Pro had Campagnolo horizontal/adjustable dropouts, I suspect the RRA had to have something "different".
Nowadays, I see more "semi-vertical" dropouts on the bikes I happen to peek at!
All the best,
Chuck Brooks
Malta, NY