Re:
Hello from Switzerland,
Colnago called this style their Freuler geometry. It's named after Urs Freuler, the tall, mustachioed Swiss road and track sprinter prominent, if not dominant, in the 1980s. For quite a while, Colnago used these extended seat and head tubes on most frame sizes over 60cm.
Here is a picture of an Atala in the same style, piloted by Urs himself. If you come across one of these in 60-62cm, I'm interested.
When using a Freuler or similar frame design, make sure that the seat post is longer than usual for a road bike; many vintage/retro/classic posts aren't. I hope that the silver Deda post which The History Man ordered for his Roberts is long enough.
If the seat post does not extend down past the junction of the top tube, seat tube and seat stays, you risk bending the seat tube above the reinforced area. Colnago recommended at least 200mm of seat post inside the seat tube in their warranty fine print.
Whatever it's called, as a relatively tall guy with longer than average legs, I like it. For more information, Google search on freuler frame or freuler geometry.
Cheers,
The Kid