On Thu, 05 Jul 2007 23:00:54 GMT, Jack Taylor wrote:

Pardon my ignorance, but what signaling problems would affect the use
of SDO, such as not releasing the doors in the rear coach?

Sorry, I wasn't very clear on that, was I? Willesden Junction will only hold
three cars.

....in the eastbound direction. The westbound platform is long enough
for 4 cars.