Great Britain #100 Cancellations

Can anyone help me identify the cities these two stamps were canceled in?
Thank you for your help.

Cities = Both London.

1. THROGMORTEN AVE (Registered)
2. LEADENHALL St BOEC (Hooded) New Discovery Only Known Code LB (At Top)
Usage 1885 to July 1887
BO = Branch Office
EC = East Central (London)

wiki
Throgmorton Street
History

Throgmorton Street in 1955
It is named after Nicholas Throckmorton,[1] chief banker of England during the reign of Queen Elizabeth I and the head of an ancient Warwickshire family.

The London Stock Exchange occupied the southern side of Throgmorton Street from 1972 to 2004. It was also once the location of the Austin Friars home of Thomas Cromwell, King Henry VIII's chief minister.

Throgmorton Avenue runs from Throgmorton Street to London Wall: it is a private road belonging to the Drapers' livery company and Carpenters' livery company with gates at each end; there is also pedestrian access form Copthall Avenue and Austin Friars. The gates to London Wall are controlled by the Carpenters' Company and are open between about 7 am and 7 pm on working weekdays. The livery halls of both companies can be accessed from the avenue, as can Drapers' Gardens; the Drapers occasionally use their hall's grander entrance on Throgmorton Street.

LEADENHALL STREET

Roman Mosaic found in Leadenhall Street 1803
(Bacchus)

If there is a Nobel prize for philatelic erudition, I nominate rod222.