Tickets for journeys routed for travel 'via London' and marked with the 
"Maltese Cross" symbol, include the cost of transfer across London by 
London Underground or Thameslink train services. Tickets displaying the 
'cross-London' marker are valid for travel between any two of the 
following stations appropriate to the route of the through rail journey 
being made.  

Amersham            Farringdon                Queens Park
Baker Street        Finsbury Park             Richmond
Balham              Greenford                 Seven Sisters
Bank                Gunnersbury               South Ruislip
Barking             Highbury & Islington      Stratford
Blackfriars         Kensington Olympia        Tottenham Hale
Blackhorse Road     Kentish Town              Tower Hill
Brixton             King's Cross/St Pancras   Upminster
Cannon Street       Liverpool Street          Vauxhall
Charing Cross       London Bridge             Victoria
Ealing Broadway     Marylebone                Walthamstow Ctl
Edgware Road        Moorgate                  Waterloo
Elephant & Castle   New Cross                 West Ham
Embankment          New Cross Gate            West Ruislip
Euston              Old Street                Wimbledon
Euston Square       Paddington

NB : As of Sunday, 26th September 1999, the following stations will no
longer be available for Cross London transfer:

Balham              New Cross
Brixton             New Cross Gate
Greenford           South Ruislip
Gunnersbury         West Ruislip