Yes I know about the '50s record high: 200 million passenger trips. And that was despite the network receiving no major works since before the depression, many more single tracks, operating a lot of shorter lines (like the two stations on the Kew Line-supposedly you'd be lucky to see half a dozen people on the train), etc.
But guess what: 2006-2007 was 201.2 million. And its still increasing.
Dont misunderstand, a big issue with this is the DoTs (lack of) management.