Look, I'm no qualified mathematician, but let me do some simple calculations:
A Mk2 Standard Class has 64 seats if I'm not mistaken, a Mk2 First Class has 42 seats if I'm not mistaken.
For reference wiki says a 5 car voyager has 246 seats (class 221), or a 4 car has 200 seats (class 220).
Let's be generous and say each loco hauled set had only 7 coaches, which before voyagers, most did; so (5x64)+(1x42) not counting any RFBs or Kitchen cars = 362 seats.
It is noted you get about 2 XC services per hour north of Birmingham/Derby; I'm not counting Nottinghams since those were apparently 158s at one time, and still sometimes 2 car 170s.
With 362 seats, you get less than 2 voyagers (even 2x4car), but with the added advantage you can walk through the entire train. Keep in mind some loco hauled sets had 2 first, or 6 standard class in a 7 rake, so more than 362 seats.
Now let's take D6975's example from post #104 of 13 coaches, presumably from the 1970s and 1980s.
From looking at lots of pictures, they seem to have a BG, Kitchen car and a BFK or BSK, so you're still left with about 10 full coaches. For example that's 7 standard + 3 first, giving you 574 seats, plus the BFK, Kitchen and BG. Even with just 10 coaches, for eg. BG+(5x64)+Kitchen+(2x42)+BFK, you get 404 just in the full seated coaches.
Now it may have been a while ago, but pretty much, we did used to have more seats on cross country trains, and you could walk through the lot, it's painfully obvious.
Yes I know we get double voyagers from time to time, but let's be honest how many times have you seen a 4 car voyager turn up...
And yes I know they're decent trains, just too short.
With rising passenger numbers in 40 years we've had... less seats and now 7 more voyagers, that you still can't walk through if it's double? I just don't see how anyone can argue our current situation is better.
www.google.co.uk
