The average London bound commuter train is built to hold approximately 480 People. (8 Carriages of 60 seats). It's a hefty assumption that they believed that those trains could run to a profit with one bum on every seat but I would imagine that's the point. Some horrible fag packet maths has that train valued at about £3840 in revenue. (Call it a very conservative £8 a seat. It costs that from my station and the train is always 90% full when it arrives, all of whom have paid more)
Considering the fact that most trains will have around 30-40 people standing per carriage, we can adjust that figure to a round £6k. Or £10k for a 12 carriage train. My station/route alone, for the 7-10am rush hour window will kick 12 trains into London Victoria for a value of £72k. Just over those 3 hours.
I know these numbers are very approximate, but they get big, quickly. If you stand on the platform at any major London station, you're seeing packed trains arrive every few minutes. I know there are costs involved, plus a daytime service to run, some of which probably run in the red, but the numbers involved are obscene.
Train companies are not forced to run humane services. They build plush trains that look pretty, built to hold 60 people comfortably per carriage. If it were me, I'd nationalise the whole lot, build trains with plastic seats, no internal glass, sure as hell no tables(?!?), straight hand rails, proper sliding windows, no air con, heaters with a thermostat and not just an on/off switch, no wifi, sectional luggage racks, at least one standing room only carriage (that would fill up last obviously), plus a bunch of other stuff I haven't thought of yet.
People need to face up to the fact that London and it's surrounding areas are massively overpopulated and while people may expect creature comforts, what they need is a functional rail service, capable of moving huge numbers of people, in an acceptable level of comfort, for two 3 hour blocks at the top and bottom of the day.
It's not that our railways couldn't cope with extra people, I'm sure it could cope with all cars being swapped for train tickets, but not with trains, and the operators set up in the manner that they are.
If you ever want to question the future of humanity, stand on a Platform at Clapham Junction at 8am, and watch a train leave every 30 seconds, full of sardine like humans eating armpits in a tin can with steamy windows.
So no, no evidence, but a bunch of thoughts and feelings.