On 2014\12\13 19:58, Michael R N Dolbear wrote:

"D A Stocks" wrote

"Michael R N Dolbear" wrote

Your ticket will be accepted on London Underground Jubilee Line
services from London Waterloo – London Bridge only.

In the event the Jubilee Line becomes so overcrowded as to be unusable
what
(apart from armies of on-train ticket inspectors) would stop someone using
the Northern Line via a change at Kennington (or even Euston!) instead?

Or via Elephant & Castle.

Nothing, unless you are gripped on the way and even then it's unlikely
to be noticed.

Would an inspector care provided you were still in Zone 1 ?

Your National Rail ticket hasn't given you carte blanche to use all of
zone 1.