Those specific figures come from the sheet "Rail subsidy per passenger mile by Train Operating Company (TOC): DfT franchised train operators: 2015/16"
Note this importantly doesn't include Scotland, Wales, Merseyrail (public) or TFL (public)
Rail subsidy jumped after railtrack was replaced with nationalrail, and the legacy of decades of underfunding in rail under BR was apparent. That underfunding is obviously going to happen under a tory government interested in cutting short term costs. You can see that as of 2015 subsidy per passenger mile was about the same as it was in the 80s and 90s[0]
Rail subsidy is split into two parts
1) Track costs
2) Service costs
Your figures are including major capital expenditure - specifically HS2 and Crossrail, so not really comparable with subsidies in the 70s and 80s when there weren't massive capital programmes and expansion.
I'm less concerned about track maintenence costs or track capital costs -- that's like the government paying for road maintenance or new motorways - it's good. It's the service subsidies that interest me. Basicalyl how much is the taxpayer using to subsidise rail travellers (who tend to have higher income and higher wealth than average), and during the 6 years I have data on, those dropped by £1.4 billion.
Remember that under BR there were competing sectors - intercity, regional railways, network southeast, all of which were shit. Now there are competing franchisees, some of which are shit, but we often get a choice (Virgin vs Chiltern vs London Midland for London-Birmingham, XC vs TFW for Crewe-Bristol, etc. This means more choice and cheaper fares for me, the passenger).
In 2015/16 the franchise "GTR (Thameslink etc)" pays £278m for the privilige of running trains through central London. Meanwhile Northern, which have very few routes that pay their way, get paid £122m from central government. You could argue that Grant Shapps would be better running these services, I'm not convinced.
Effectively Brighton->London commuters are subsidising rural travellers in Yorkshire. You could argue this shouldn't happen, and those commuting into London for high paying jobs should have cheaper fares, at the expense of fewer services in the North. That's a very Thatcherite view, but that's ok, everyone's entitled to a view.
APT predated privitisation by 2 decades so I'm not sure what that has to do with anything. Virgin ordered the class 390s.
It sounds like you don't like the state of the rail industry in Britain in the 80s and 90s, which is reasonable. It's hardly the fault of privitisation didn't start until 1993 and didn't begin operation until about 1997
[0] https://en.wikipedia.org/wiki/Impact_of_the_privatisation_of...