On 14/05/2010 22:46, trainmanUK wrote:
I went from Piccadilly Circus to Kings Cross on the piccadilly line.
I went to the Eurostar ticket office to buy a ticket which took about
10 minutes. I then went from Kings Cross to Paddington on the
Hammersmith and City. These were two separate journeys but seem to
have only been charged for one.

Perfectly correct. King's Cross St. Pancras (Tube) - King's Cross St.
Pancras (Met) is one of several "Out of Station Interchanges" possible
in that area, with a permitted time of 15 minutes between touching out
one of the Tube gate lines and touching in at the Met one.

If you touch back in after more than 15 minutes, it's treated as a new
journey.

Cheers,

Barry