Glenn E. wrote:You just need a year in which the single vineyard got a slightly different (and better) weather pattern than the estate as a whole.
Saying this got me interested, so I've been doing a little research.
Quinta dos Malvedos is primarily a South facing estate in the upper Douro east of Pinhao. But the Port Arthur vineyard is East facing, and the Vinha dos Cardenhos is actually North facing. So those two vineyards will have pretty dramatically different terroir than that of Malvedos as a whole. I will be surprised if they aren't able to produce Stone Terraces in what would otherwise be non-vintage years, though they may still choose not to do so. The two vineyards combined are roughly 1.8 hectares so Stone Terraces will always be very limited production.
Quinta de Vargellas is primarily North facing, though its terrain is relatively complex so there are many parcels within the estate that face in different directions. Vargellas Vinha Velha is harvested from 5 small plots which are scattered throughout the estate: Polverínho, Renova do Depósito, Renova do Armazém, Gricha and Vinha Grande. There doesn't appear to be any rhyme or reason to these plots other than the age of the vines, which varies between 80 and 120 years old. They're all field blends except for Polverínho which was part of the first single-variety batch planting experiements in 1927 by Dick Yeatman. The old vines plots combined produce roughly 15% of the grapes at Vargellas, but only about 2% of the total production is used to make VVV. As Vargellas is ~68 hectares, this makes VVV production somewhat lower than Stone Terraces production at the equivalent of 1.36 hectares, though Taylor Fladgate could choose to increase VVV production if they wanted to.
Vesuvio a Capela is indeed simply a "super reserve" made from the finest grapes harvested from Quinta do Vesuvio. It isn't a single vineyard VP, so its terroir simply represents the pinnacle of what the estate as a whole can produce, at least in theory.
The Nacional vineyard is well-known amongst Port fanatics, at least by reputation if not by actual knowledge. It is situated near and just above the house at Quinta do Noval, but its terroir is probably affected more by the devoted care provided to the vineyard than by its location. (Though its location surely also plays a part.) The vines in the Nacional vineyard are ungrafted which means they are vulnerable to phylloxera. Phylloxera's affect on a vine (before killing it) is to stress the vine and make it struggle as the roots are destroyed, so at least in theory the vines in the Nacional vineyard should produce "older" than their actual age. It's very easy to see why the Nacional vineyard might produce in non-vintage years, or might not produce in vintage years. It's just an entirely different vineyard than anything else in the Douro. The Nacional vineyard is about 2.5 hectares, so its production is slightly higher than that of Stone Terraces or VVV though still very limited.