Electric stock is great.
But we are on a network where there's so little juice that the hourly extension of the TPE service north of Newcastle is having to run on diesel mode from Chathill to Edinburgh - whilst I'd love something like an 802/804 for XC, there may be issues on the network where there wouldn't be enough power to draw, so they'd end up staying on diesel mode (e.g. I wouldn't be hugely surprised if there were initially problems with a hypothetical "tri-mode" Voyager replacement from Reading towards Bournemouth.
So, whilst I'm not a fan of the Open Access plans for Blackpool/ Liverpool, I could understand if Virgin had to run on diesel because the wires didn't have sufficient power in them for this additional service - just speculating though