Dave Arquati wrote:

As other posters have suggested, Aldwych was probably doomed from its
birth. If Aldwych were reopened today with through services to Cockfosters
(which in itself is physically difficult), I think demand would still be
poor for two reasons:
....
2. Even if served by a relatively high frequency, it's just too near other
Piccadilly stations to be particularly useful - even Holborn is only a few
minutes' walk away, and Covent Garden is much more useful for the key
theatre-going market.

And yet which station on the Picadilly Line is so over capacity that it
frequently has to limit passenger access and could really benefit from a
nearby alternative station?