Extending their maintenance and incident response coverage deep into the countryside sounds kind of inefficient as does maintaining a micro-fleet with very different characteristics to the rest of their trains.
Would there be a micro-fleet?
Alstom still market the 'Movia' product, so I would assume that the service to Aylesbury would simply be run by another batch of S-stock. Assuming the fall in peak traffic since coronavirus is not sufficient to cover the extra diagrams by stretching the fleet.
Chiltern currently maintain a microfleet of units fitted with tripcocks to operate over this route, so transfer to LU would likely lead to greater, not lesser, standardisation.
What's more I don't think it's at all guaranteed that DC conductor rail electrification of the Aylesbury line would be sanctioned just because it's TfL. I doubt that line will match the levels of segregation that most LUL infrastructure has. In any case, I am opposed in principle to extending 3rd rail electrification to places where it doesn't already exist - this, to me, doesn't seem like an obvious extension of pre-existing infrastructure like is the case with the Uckfield line or Guildford to Redhill. In part because of the possibility of a connection with EWR, and national rail services that would still be interacting with Aylesbury from Princes Risborough.
Aylesbury is well enough provided with platforms that services could be kept seperate if it was desired.
I also can't see any real purpose to running trains from EWR onto the northern Metropolitan line, it's not a fast route at the best of times.
As to extension, once a handful of footbridges are built, I can't see how its fundamentally different to any other section of London Underground surface running.
That ORR specifically did not extend its presumption against approval to LU installations is very telling, in my view.
This line has been an awkward add on to the British Rail/Network Rail system since the Great Central Main Line was axed.
I think a major lesson of the last several decades is that people don't care that much who runs the service, they care that the service is run.
Sure, it extends a substantial distance beyond London, but the railway must cleave first to railway geography, not political geography.
LU operating this stub and allowing Network Rail to wash its hands of it seems the most elegant option available. Just as transferring the Waterloo and City line to London Underground made sense at privatisation.
Having the line become part of another crossrail scheme is probably the most sensible solution with Met services cut back to Watford and Uxbridge only - that way you can strengthen service on the sub-surface main circle.
I'd say running the Aylesbury line as part of the Met is an idea probably more strange then just wiring the whole line including to Chesham and cutting the Met to Watford. I'll concede that issues facing that would be capacity on between Marylebone and Harrow probably requiring a grade separation of the junction at Neasden and the high number of overbridges between Harrow and Aylesbury which would slow the programme down.
That's all going to be extremely expensive.
There does not appear to be any money for this.
It's ~46 track kilometres above Amersham alone, which at current prices for 25kV will be something in the region of £90-180m. Let alone any work south of Amersham.
