Sorry I am new to the area and would like to learn more about the demise of First. I know that First used to have a large presence in Thames Valley which has since shrunk. What led to the failure of First while other companies, Carousel for instance, manage to flourish?
First lost 2 bus wars and subsequent council tenders in Maidenhead and Bracknell in the 2010s, repeatedly losing to the small independent Courtney Coaches. The owner, Bill Courtney would later sell the company to Reading Buses and it was merged into their Thames Valley operation (which was initially started in response to First's withdrawal from Bracknell and network changes in Slough and Windsor).
Courtney ran new, leased buses such as Optare Solos, whilst First ran a mostly motley fleet of older Barbie liveried low floor buses, cascaded buses from First London and older Citaros bought by Heathrow. First also relaunched the Beeline brand in a unsuccessful attempt to win back custom in Bracknell. Beeline was the name of the operator before it was purchased by First Bus.
First's operation in the Thames Valley was at the time being overseen by management in Southampton. They made a number of major changes to return the remaining Slough operations to profitability.
After pulling out of Bracknell and withdrawing their Greenline 702 service, they withdrew from tendered routes in Slough and Windsor, then broke up cross town routes in 2017 and after temporarily losing Heathrow funding, axed several direct routes to the LHR terminals. They also stopped serving the local general hospital at Wexham Park.
The Slough cross-town routes were eventually reinstated with higher frequencies with new funding from Heathrow. A change in management saw a rebranding back to Beeline for the 2nd time with newish cascaded double deckers from First Glasgow. First have been more focused on expanding their Heathrow RailAir coach shuttles in recent years than bus routes. Slough depot is also a base for the coaches they now run for FlixBus.
Thames Valley and Courtney (prior to the takeover) took over the tendered routes dropped by First in Slough and Windsor. Reading Buses launched a replacement Greenline 702 commercial service run from their depot in Reading. This was later complimented by the 703 service run by Thames Valley between Heathrow T5, Slough, Windsor and Bracknell, funded by Heathrow.
Carousel initially got a foothold in Slough by running some Sunday tendered services to High Wycombe on the 74, they then expanded onto the Amersham-Gerrards Cross-Wexham-Slough routes and launched a commercial service to Wycombe via Beaconsfield a few years after Arriva withdrew the 74 route. Carousel have gradually taken opportunities to expand their network over time, initially taking routes from Arriva who they would subsequently defeat in the long running bus war in High Wycombe.