Forgotten object in Heart's Desire (small spoiler)

The other day I headed to Polythreme for part of the Heart’s Desire ambition to speak to the Clay Priest. Afterwards I needed to get another item to continue so I went back to London to try to find it. Only on the way it completely slipped my mind what the item actually is and the fan wiki doesn’t list Heart’s Desire that far in. In the interests of avoiding going all the way back to check, does anyone happen to know? (Even better, do they know how to get hold of it? lol)

It’s a bottle of 4th City Airag (sp?), which you can get by trading 5 cellars of wine using the Presumptuous Opportunity card.