Aidan Stanger wrote:

Maybe because the Tube system doesn't have the spare capacity to cope
with the passengers who currently walk from the NR station because of
the economic incentive to do so.

If you're referring to season ticket holders then it's probably almost just
as quick to walk depending from the London station to the office or
whatever. Those coming into London Bridge, Cannon Street etc. are obvious
cases. Several of my colleagues commute in from the lines into Charing
Cross and walk from there to work which is mid-way between Piccadilly
Circus & Green Park. Currently they have point-to-point NR seasons.

--
Phil Richards
London, UK
Home Page: http://www.philrichards1.pwp.blueyonder.co.uk