The Royal Exchange is right at the heart of the City of London. Indeed, the setting of Conran's Grand Cafe & Bar could not be much more imposing. It is a very grand place to meet, whether for a drink, a meal or a party.
Note that the central courtyard fills up very quickly indeed, but if you go up to the mezzanine floor, there is a lively bar on the left and an enticing restaurant on the right (assuming that you enter the building from the front).
Although it is near impossible to book a table at Grand Cafe & Bar, good timing helps! If you want lunch, in particular, make sure that you come early or later. The Grand Cafe & Bar tends to get packed out around 1pm.
The food, however, can be rather good. The company is sometimes even better, particularly if c shows up!