It's been quite a while since I regularly used the tube, but one thing
not to my taste was buskers in the carriages. There were two in
particular: the first was a scruffy yob with a crap guitar who plagued
the Piccadilly line from Heathrow - the incoming tourists loved him
"Gee so this is London's cool music scene"; the second was a
travelling band of Peruvian (?) players in national dress, complete
with drums and panpipes, who used the District line in the central
area, and were quite intrusive when pasing the hat round at the end.

The right place for buskers is at the end of the escalators or in the
interchange areas (not platforms) where you are free to give them
something or not, and are not forced to listen to them for long. ISTR
LUL now has some sort of "Approved Busker" scheme of this nature, but
do you still get the itinerant noise-merchant in the carriages?