In message , at 22:15:12 on Thu, 29 Dec
2011, Clive Page remarked:
But a question: to get from T123 to T4 you have to change at Hatton
Cross don't you, as all trains go clockwise around the route. I
presume that's allowed free on the new Oyster-card arrangement?

It says "journeys between", without ruling that out as a route, indeed
it's the only route.
--
Roland Perry