On 31 May 2007 03:58:52 -0700, Mr Thant wrote:

Is it permissible to go shopping while transferring from DLR to Jubilee?

Yes, but if you spend more than 15 mins outside the barriers it counts
as 2 separate journeys.

Has anyone actually verified this 15 minute limit? In the early(ish)
days of pre-pay, I took a 25-minute OSI between Baker Street and
Marylebone, and was still charged for one journey. (However,
Marylebone may be a special exception, as you have to wait outside the
barriers until your train is announced.)