Belated confession...I did not actually realise that the bottle of Hermitage I brought along was white wine until I arrived at the restaurant! I have done some comparison with an old empty of the red Hermitage (Shiraz/Syrah) from this maker and the bottles and labels are pretty well identical, and very easily confused if you don't look carefully.
Still, the quality of the wine was certainly remarkable, specially for white of this age. as several people commented, It is apparently a blend of marsanne and roussanne which hardly exist in this country.
However, next time I will try and pay better attention!