When I first visited the Stag's room, I was surprised by how cosy the place is. i think the maximum capacity is about 20 guests in the seating area, and they have a "private" glass cellar room for about 8 people max if you really need to have private conversations. It's not as comfortable as the table and chairs are high, and it's probably used more for busier wine tasting etc.
In the main area, the leather seats were very comfortable and the place was a great delight to my friends who experienced the stag's room for the first time. Service was attentive and top notch.
The downsides, the wine was a bit on the high side - but it's really good value with the great comfortable venue and top glassware. Snacks were also limited, so the focus is really on the wines. They didn't even have whisky or other alcoholic drinks, which they said were available at the champagne and oyster bar next door (which is a bit more rowdy). They also close fairly early. Last order was 11pm but they stayed open for us till 12 midnight. Kudos to the personalised service.
I'll definitely be visiting Stag's Room again, and it's a highly recommended place for catching up with friends, or even business meetings. Heck, I might even just go there solo and enjoy a glass myself with a good book. Go check it out, you won't regret it.