What are people wearing for smartish evenings out in Londond?

[strawberrythief1]

I've been invited to a friend's birthday party for a significant birthday. It is going to be in a relaxed but smart restaurant in London.
I haven't been out in London for so many years that I haven't got a handle on what people are wearing nowadays.
Is it better to go slightly on the casual side or do people tend to dress up?

I have a couple of dresses that can be dressed up or down and the usual jeans/ heels. Any suggestions?

It's fine to wear smart jeans and a nice top but I think it's always better to be overdressed. If you have a really nice dress, I'd wear that. What options do you have?

I see a lot of glam hair and striking lippy when I go out (not often these days!).