Just realised this area was here. I have mentioned the sale that I am in charge of at Tennants in another post (check the Whisky Events forum), but that was relating to the malts.
Now....19th century cognac...very rare. But there are around 20 lots of it in the same sale as the malts.
Some of the highlights are: a pre Battle of Waterloo bottle of Denis Mounie 1808 (£800-1200), an 1811 bottle of Chateau De Fontainebleau (£500-800) , and a whopping DOUBLE MAGNUM of Camus Grand Champagne Cognac, 1875 (£800-1200).
There are quite a few others worthy of note, like the magnum of 1811 Grand Fine Champagne Imperial, Martell 1877, even modern classics such as Lafite Tres Villages, £100-200, but I am sure you all have your favourites.
The sale can be found at http://www.tennants.co.uk/Catalogue/Sales/184.aspx and then just use the dropdown menu to find all the cognac lots.
I hope you cognac guys like this...