Class 377s on loan to SE back to Southern, Class 465s now in storage back to mid distance routes after heavy refurb? Removes Coastway 313s?
Why refurb 30 year old units ? They're closer to end of life - if they were up for a mid-life refurb that should have been done about 10 years ago.
I suspect part of the answer to Southern's 313s is more related to the 387s that are currently with GN and could be replaced by the 379s which GA have replaced with their Stadlers. And then the 455s also need to go - which is most likely a new build with appropriate interiors for what are largely 'inner suburban' type services - so Desiro City or similar.