This alley is (or used to be) called Crosby Square. The street name sign was visible on 29th April 2019, at that point on a building hoarding. Now the street name has disappeared. It is of interest as this is the original location of "Crosby Hall" built in 1446 and later moved to Kensington.
The alley now goes underneath the new building "22 Bishopsgate". It emerges onto Undershaft I think, but is currently blocked by building work.