@Words Snorfle, you're so funny and sweet. Dean Street Townhouse is routinely described as 'luxury' and 'upmarket' but it is really a fancy boutique hotel with a bar and restaurant attached, rather than a restaurant. It's owned by the Soho House group, so its media-based membership probably helps account for its - in my view - rather puffed up reputation for fine dining and excellent wine list. In common with all the Soho House establishments, the best bit is generally the building and the decor. You probably wouldn't go for the food, which was nice enough, but nothing special. I guess the members enjoy the networking opportunities.
Jeans are commonplace everywhere nowadays. The last time I went to the Royal Opera House, some people were dressed as if for a trip to the garden centre. Poor things. No sense of occasion.