"Paul Scott" wrote

Use the current platform while rebuilding the old platform to modern
standards over the necessary length, say 8 coaches?
A temporary, moveable flat bridge would be needed to access the currently
in use platform. Demolish half the current platform (you'd to retain a
four
coach lengh for the current service) and provide the new running line in
front of the renewed old platform, as a short platform loop off the
through
line. Then demolish the remaining current platform and extend the loop to
whatever length you want to allow for increase line speeds on entry/exit.

Alternatively, having completely rebuilt the old platform, demolish the
current platform and provide the full length loop in a 'big bang' closure
of
a few weeks.

I also suspect that if they were to do it now, the weekday timetable could
be worked with one platform. Once the LO service frequency is doubled that
will probably no longer be possible.

It could be done, but sounds disruptive and/or expensive. But what's the
point? There's no need for passenger trains to be able to overtake each
other on the WLL. There is occasionally a need to recess a freight to match
a path on the next stage of its journey. In many cases this can be done at
Willesden/Wembley, or between Culvert Road and Latchmere Junctions (even
when ELLX gets to Clapham Junction). The existing through line at Kensington
Olympia can be used in both directions. If more flexibility is needed the
pointwork at each end of Kensington Olympia could be relaid to reduce
conflicts between up and down train (at present a southbound train using the
through line conflicts with a northbound train at, IIRC, both ends of the
station). Or a new goods loop could be provided south of the station.

Peter