Oh, I missed this. Doorway at no 160, totally anonymous except for signs saying 160 on door pillars and sign "door not in use" stuck on both doors with vague arrows pointing left and right. But there are no other doors (other than those of Moorfields Hospital. Clearly they don't want visitors.

Anyway, https://www.companieshousedata.co.uk/a/2054142 shows this door also uses the postcode EC1V 2NX -- and shows "There are 3576 companies at this address".

Clearly, those 3576 businesses are only using the building as a mailbox, do not have any mappable physical presence. 

We should keep a lookout for businesses with that postcode and ensure they do not accidentally get remapped without proper physical signage.