"Tom Anderson" wrote in message
...
On 29 Dec 2003, Thomas Crame wrote:

The service could have been disrupted, and the controller may have
decided to run one, either to get a train back to time or if Olympia
has had a long interval without a train. I've known Circles to be
reformed into Hammersmith's en route before now

I was on one when it happened once: it was a circle as far as Aldgate, and
then changed; i never thought i'd be leaving Aldgate on a H+C train!

A very common occurrence in recent years. I've also been on H&Cs that became
Circle services upon reaching Liverpool Street.