In message
,
lonelytraveller writes

Why didn't they direct anyone to the northern line's emergency stairs?

I think the short answer is that the fire was initially thought to be
small, and that evacuation via the Victoria line escalator was thought
to be safe.

Add to this the fact that the station had no evacuation plan, and those
initially trying to evacuate passengers were two Met police officers and
six members of the BTP (BR Eastern Region), none of whom had any
detailed knowledge of the station's complex layout. The Fennel Report
said that the two Met officers genuinely believed that the Victoria line
escalator was the only other available exit. Even when the fire brigade
arrived, they couldn't access the station plans or communicate with most
of the LT staff (the infamous radio problem) and so they, too, were
probably unaware of the emergency stairs.

In the end, most of the passengers from the deep-level platforms were
evacuated by tube (Victoria line), which was probably safer than
encouraging hundreds of panicky people to attempt the long climb up the
emergency stairs.

--
Paul Terry