The back two carriages are empty - Usually what happens is that they separate into a new train, which follows the front four carriages after a gap of six minutes.
This morning the two parts of the train were split only with great difficulty and some delay.
The consequence is that we are now running 10 minutes late, it was standing room only from Beaconsfield and I yearn once again for the Yuletide solitude on the trains.
They might as well have joined the two trains back together. Actually, I've just remembered that they can't. The four Clubman coaches rapidly turn into the 0750 fast Birmingham service from Marylebone, so they wouldn't want two slow carriages stuck to the front.
I guarantee we'll be fighting off Birmingham bound passengers as we try to get off in London.