In message , at 21:35:41 on Fri, 27 Jun
2014, MikeS remarked:

The National Rail Enquiries journey planner mostly works fine for rail
journies through London requiring a tube connection between two national
rail stations. It rarely gives the easiest (or even a sensible) route if you
specify a national rail destination in London for which the best option is a
rail journey to another rail station followed by the tube.

If you ask it for trips from Stansted Airport to Kings Cross it will
default to a train plus change to the tube at Tottenham Hale. Or
Cambridge to Liverpool St where two of the hourly suggestions is to go
via Kings Cross and tube.

And I'm familiar with both of these appearing in results.

On a weekday it happily suggests Cambridge-Moorgate via a change at
Finsbury Park, but the latter NR service doesn't run on Sundays.

I have no idea if this is a fault or by design (assuming that if you
specify a national rail destination you want to arrive at it by
national rail).

The problem with my Sunday journey to Moorgate might be the existence of
"Moorgate Und 0645 ZMG" in addition to "Moorgate 6005 MOG", and
unfortunately the NRES planner doesn't recognise the former as a
destination.

Which I suspect is a fault rather than 'design'. Especially given the
alleged inter-availability of "London Terminals" tickets to Moorgate on
both NR and on the Circle.

I have never expected to use it in the way you describe any more than I
would expect it to tell me the correct use of a bus in some other city
when completing a journey by national rail is possible but not a
sensible option.

Despite your misgivings, it does have numerous tube-only destinations
available. Try Holborn for example:

Train 10:15 Cambridge [CBG] London Kings Cross [KGX] 11:05
Tube 11:20 London Kings Cross [KGX] Holborn London Und 11:24
--
Roland Perry