The M23 has been running for a month or so having been extended north of Newcastle (previously M22) through to Scotland. The northbound service leaves London at 2345 and arrives in Glasgow at 1310, having stopped at loads of places (Finchley Road, Northampton, Rugby, Leicester, Loughborough, Nottingham University, Nottingham, Tibshelf, Meadowhall, Leeds, York, Middlesbrough, Durham, Newcastle, Haggerston Castle, Dunbar and Edinburgh) on the way. I assume the 1645 south is the same Interdeck that works north.
In a way it is a bit like the old M12/M19 which used to leave London at 0100 and went via Leeds to Manchester and on to Glasgow. That got cut back to Manchester after a few years and latterly had a Liverpool extension. That used to call at a Tesco off the M1 at Milton Keynes and didn't go into Nottingham.
To think that Rugby was once the key part of the operation, with a lot of the coaches carrying Midland Red South lettering. Rugby changeovers were a common occurrence on many of the north-south routes.