It sounds like the plan is that the government will renationalize the railways but behind the scenes companies will own the trains and like you say lease them to the government. They won't actually operate the trains they'll be done by government employees.

Presumably there will be some kind of price cap on how much the government is prepared to pay per train. But with the emphasis on making money removed it's possible we'll see all those little lines that don't really make any profit reopen.

This is actually good, trying to make money from public infrastructure is a dumb idea as it leads to cost cutting measures that essentially make the infrastructure useless. The profit turns up in other areas of society.

How it generally works now is that the operators win a contract from the government to run a line for X years. They pay the government for that contract, then have (as a for profit company) to make enough money to make a profit on top of that. There are various rules though on the fare increases allowed (hah!) and the contracts generally include minimum service levels etc.

The actual tracks and signals are run by network rail who are a state owned company that own most of the infrastructure (replaced Railtrack who were an actual public company that went bust!)

The stations are managed as part of the operator contracts I believe? Unsure on their ownership.

Because the operator's contracts are time limited the operators can change over time, when that happens though the rolling stock (trains) are generally transferred with that, either through being sold to the new operator or leased. (It's not like you can order a new fleet of trains and get them delivered on short notice!)

My understanding is that labour is mostly going to take over the running of each contract as it runs out instead of buying them out. I assume they are then leasing the trains to avoid the up front expense of buying them all. As they won't be trying to make a profit it (should) be possible to run a cheaper service and could/should allow the lines to be run for the public good instead. (That's where people opinion of public ownership comes in)

There are already some lines run like this as the operator went bust and it defaulted back to government control.

Currently Network Rail owns and operates (nearly) all the railways, signals and ticket offices. Not sure about stations. Train companies rent rail stock, but they pay a high price for this and subsequently pass that onto the consumer, while maintaining that it's necessary to charge expensive fares because their costs are so high.

The government owns Network Rail. The government will take over the rail companies, and this will probably end up staggered as different companies have different contract dates. The rail stock itself will probably remain under the same ownership with more or less the same ridiculous rental charges.

So all in all this probably won't make that much difference.

Rail track is owned by network rail. Under the government but run privately.

Stations are run by train companies.

Trains used to be owned by banks. And rented to train companies. Not sure its still banks. But def rented from a privrate company.

So this would start to see arenationalised network rail (minor changes to how its run basically) renationalisation of stations as contracts to run them expire. They already belong to government/nation

And renationalisation of routes as contracts run out. Renting the same trains the current companies rent. Of course currently those companies have to kit out the trains themselves. They literally rent empty carriages. So its likely the renationalised company will have to consider that.