And a visit later for a Chocolate Bombe...
Jackson + Rye is a great place for brunch, or to stop for a pudding... located on Wardour Street its within walking distance of all the main Theatres.
If you're in a small group you should be able to just walk in and get a table within 15-20mins, but I'd recommend if you're in a group of 4 or more to call ahead and reserve a table, or you could be waiting a while!
I've never had dinner in Jackson + Rye, but having sampled the brunch and the dessert menus I'm definitely going to be coming back soon. I am currently drooling over the pre-theatre menu's chargrilled red snapper followed by the toasted marshmallows with orange sorbet and chocolate sauce.