A few things to note:

The green (Mark II) coaches, 3 of them, I think, including a Buffet,
have been in the siding since last week, when there were no Class 33s
there.

Also, at the end of last week, one of the black Class 33s was parked in
the run-through line between Platforms 2 and 3 on the Windsor side of
the station. This week, a rail-clipped marker light was still in place
to the West of where it was parked, acting as a temporary buffer/stop
light presumably.

But, most interestingly, on Tuesday around 8a.m. there was a steam
loco in the electric sidings approaching Plough Lane. I couldn't make
it out, but it was facing West, and presumably was there in connection
with the Cathedrals Express.

Given that they have been there all along, however, I don't think that
the 3 green coaches had anything to do with that train, unless they had
been removed from the rake for one reason or another.

Marc.