92043 could of course travelled under its own power down the WCML.
I have read that the 20s took it from Brush as far as Stafford.
Exactly (re WCML) - hence the move was a bit odd/unusual. Unless for some reason 92010 needed a tow down to Doncaster. It's been running fine recently, though, so no reason it would've done.
Maybe due to locations of drivers, pathing costs, whatever it was better for them to do it this way rather than send 92010 solo down the ECML and 92043 from Craigentinny down the ECML.
I'm sure someone will pop up on here soon and explain why...!
And, yes, the 20s dropped 92043 off at Stafford and returned to Doncaster, with the 92 making its own way to Crewe. There's a video of it just gone on the YouTube.
2+2=5 probably, but I'm wondering if 043 is at Crewe for the time being to act as a "Thunderbird" with all the recently modified CS 92s getting back into service?