Yes, there are plenty of recognisable things on the menu
and (at B&W at least) several extra dishes on a specials board , but it's not always clear from the description how they'll be prepared. The staff are happy to tell you of course. A dish of Wigmore and potatoes is just that - a piece of cheese and some new potatoes. Doesn't appeal to everyone.
Some people find the small plates offputting. One friend won't go to our excellent local tapas bar because "they do bits and pieces, you can't get a proper dinner". This objection wouldn't apply to St John itself of course.
Apologies for going off topic!