I don't know how I first came across this pub but I always seem to end up going there before or after the theatre - it's tucked away off the main path, so you wouldn't just come across it.
It's small and so can't help but have a great atmosphere (because you're all on top of each other) and they do a good selection of trad ales too.
Popular with theatre luvvies, locals and office workers, Nell Gwynne is an intimate venue with a deep red decor that serves a variety of drinks and light snacks throughout the day.