cj wrote:

I'm just curious as to what stock Southern will use for this service -
seems a bit of a waste to have one of their DMUs so far off normal
territory for a good few hours. Unless dual-voltage stock is possible
for the whole route - how would it get from Ealing to Shepherd's Bush?

It will have to be a 171 [as it isn't an electrified route] - there is a
section in the track access application that covers it:

"Southern propose to use class 171's units as standard specified equipment
to operate the Wandsworth Road to Ealing Broadway passenger train slots ...
subject to route clearance."

The unit won't be travelling too far, it would quite probably be one of
those stabled at Selhurst between the peaks...

Paul S