I therefore assume they already have maintenance provision for next 7 months. That's more than long enough to get replacements that are parked in sidings.
7 Months to arrange
- Finance
- Leasing contracts
- Maintenance contracts
- Maintenance training & refits
- Maintenance cycles
- Stabling locations
- Crew training
- Stock refresh (carpets and cushions, Info screens, etc)
- Infrastructure compatibility checks (and any works required)
- Crew diagrams
- Stock diagrams
- the ad-hoc moves to get the stock from storage to refresh location and then service stabling, and withdraw old stock being withdrawn (incl. Drivers, TOC, Paths, Clearance, funding etc).
(I've probably missed some)
And DfT/Treasury approval as needed for all of the above.
Good Luck. Some of this is probably quite simple (e.g. Crew/Stock diagrams may just copy across), and some might only be temporary issues (e.g. Stabling space while the fleets are crossing over), but there's still a lot to sort out and there's the question of who'll actually be sorting it out - consultants, people who'd be planning Chiltern's day-to-day services otherwise, new Chiltern Staff?