Not sure if it does? I believe in the City's case it never has been massively party political in the sense of most London councils.
There are a few rural councils in Scotland where Independents are still pretty common too. Apparently was quite common across UK till recent decades.
there's a bunch of the Wee Free up in Scotland that skew that a bit; the City is very much its own thing too, but you might expect the tiny bit of London that has the Bank of England in to have a single represenative of what used to be the party of business and commerce
According to the sparse information on Wikipedia 2017 was the first election year out of the last three (2013, 2009) where Labour stood and it was the only national party to get elected.
en.m.wikipedia.org/wiki/2017_Ci...