After Theatre Drinks London

If you're looking for dessert, I think you may struggle to find a place serving food that late that isn't a dedicated place like an ice cream shop. You'll be very close to the Lyceum Tavern, which is one of my favourites, but that's more for beer than for cocktails or coffee. Either way I think you will find more close to the theatre (in the Covent Garden area) than you will back in Victoria, so I would be looking there.

I recommend

https://www.sarastro-restaurant.com/

We went there after a show, and it is a show after the show. We had a blast.

We are going to see Six at the Vaudeville Theatre on the Strand on a Monday in September

Check your date. There are no shows at the Vaudeville on Mondays.

Some possibilities:
1) The Opera Tavern is a tapas restaurant on Catherine St. I have eaten there several times post-theatre. They have some bar seating and I have seen people just having a glass of wine post-theatre there. They have a great selection of wines and some cocktails. If they weren’t busy, I suspect you could just get a drink at the bar and a dessert or snack. They won’t have sticky toffee pudding though.
2) The American Bar at the Savoy. It is famous but probably very expensive and they probably have a dress code. I have never been.

Thanks for the catch…it’s a Tuesday night (I have edited the original post.)

Years ago I satisfied my post-theater sweet tooth at Caffe Concerto Haymarket - there is also a branch in Covent Garden, a short walk from the theater - they stay open until 23:00.