In message .com,
Mizter T writes

I really don't know much about it, though I get the impression it
wasn't a significant service at all so wasn't a great option for pax
from Finsbury Park to the City. Perhaps someone else knows a bit more
about this?

Before the war, something like eight trains in the morning peak from
High Barnet to Broad Street via Finsbury Park, and six from Enfield
Chase (or Gordon Hill) to Broad Street via Finsbury Park. Both services
were much more limited in the central part of the day.
--
Paul Terry