Soho Square Gardens
From Jenny Everywhere Wiki
In one universe, on the way back to her London home in the Mod Rod, Jenny Cornelius dropped by “her favourite bookshop” via “a quick turn off of Shaftesbury Street and a circumnavigation of Soho Square Gardens”. (PROSE: Birds and Snakes)
Behind the scenes
This is consistent with the bookshop's reported location on Greek Street.
