On 26/09/2010 09:34, lonelytraveller wrote:

Half way through the lift journey, you'll see the passage. Then maybe
you might have an idea what it might be for, or where it goes, or why
its tiled like a public passage.

Not having sampled the Northern Line lift yet I can't comment
authoritatively, but could the "intermediate" level be one of the
concourse between the Piccadilly and Northern Lines or a link to the
(in)famous "SMILE" subway to Pentonville Road?

Cheers,

Barry