What would it take to restore the UK's rail network?

We shouldn't. We shouldn't be restoring a failed 19th Century network, we should be building a true 21st Century network.

The Victorians built thousands of miles of railway line on the basis of an investment bubble. The model was truly privatised, with companies building multiple parallel lines to undercut each others' business. Industrialists would gather investment for lines to places with little industry and few passengers.

There are three true stand-outs for excellent rail systems in Europe.

Spain has mastered the intercity network. This is about building long, straight, high speed lines, with nice clean central city stations, where trains can run uninterrupted between cities. The Victorians built us lines with lots of stops and little service seperation between fast and slow trains. This won't do. The lines are too curvy, too many stations serving small cities and large towns†, and too congested.

† Not that these places don't matter, but the success of the Spanish network shows it's best to serve them with the intercity network. A fast train rapidly stops becoming fast if it stops at too many places.

We need to not only build Northern Powerhouse Rail and HS2 in full, but then look at schemes to connect England and Scotland, London with Wales and the South West, Cambridge, and build connection between the continent and the rest of the country. There's nothing for it but new lines.

Spain has showed it's possible - with the right laws and the right decisions - to do this quickly. In the time it's taken us to commission, cancel, uncancel, recancel and reuncancel half of HS2, Spain has built a high speed national network, then gotten to the point that they're embarrassed about failing to have anticipated the demand for it, and having to build relief lines.

Germany has mastered the regional commuter network. This is about Thameslink/Crossrail-style schemes, connecting up existing commuter branch lines through the central city, and creating a regular, predictable, half-hour timetable that guarantees your commute from the exurbs and outer suburbs to the city centre. We should be looking to build these networks in all major cities. We need to learn lessons from their failed implementations in London and Manchester, and follow the German model as closely as possible.

Again, this isn't about restoring random rural branch lines. This is about using the branch lines that already exist - where people live - and using them better. Making them more useful, and more reliable. We don't need to re-open anything to make this work. We need to dig Crossrail style tunnels under Leeds, Manchester, Glasgow, and Birmingham, and expand on the (eventual) success of the Elizabeth Line in London whilst fixing the remaining issues with Thameslink.

Finally, the UK (yes, surprised to see this one here, aren't you!) has mastered the metro network. I say 'UK' but I mean London. This is about creating metro-controlled authorities with pride in their work who focus on turn-up-and-go service. TfL is a world-leader in building and maintaining these systems. We need to spread that expertise - and the political model that's supported it - across the UK.

Again, re-opening random rural branch lines isn't helpful here. This is about working with what we have - and digging a few new tunnels in the areas needed - to create metro systems. It means prioritising metro travel over fast trains, which will piss people off, but is how London has created such economies of scale.

I'm not against re-opening any closed branch lines. The Branch Line Society has identified about a dozen branch lines that are high priority for them, and I absolutely support those ones (https://www.branchline.uk/home.php). Otherwise, we shouldn't be repeating the mistakes that the Victorians made. The UK network needs rebuilding, not restoring.