Reliability of FGW Sleeper service & Cl 57's

[adc82140]

Would it theoretically be possible to adapt a Mk 3 DVT to work with a 57? That would mean there was no need to use a loco for ECS moves, effectively leaving an operational spare available.

 

[90019]

I would've thought it's be more probable to adapt the locos for the DVT.

 

[matchmaker]

You can have two back to back and use the towbar, but it's a bit risky. I think it's been done once before.
However, you can't just hook up the powercar to the coach as the coaches are loco hauled Mk3s and have different couplings to the ones in an HST.

Couplings are the same - but the ETS on a HST is 3-phase, as opposed to normal single phase as on all other stock.