These cuts in Slough seem quite brutal - I always thought Slough was a small oasis of more promising territory compared to the rest of the home counties. It is a small operation remote from the rest of First bus - does this matter? Maybe not getting the management attention it needs?
There's a number of issues. It's clearly suffered from being run at arm's length from Southampton who seem to make bad decisions. There's also the decline of Slough High Street for shopping, for instance Marks & Spencer finally pulled the plug on its High Street store this year. So why would you go into Slough at the weekend? The September 2016 change made Slough Bus Station the hub for all routes. The retail parks along the A4 are very busy, but only route 4 serves them, bypassing nearby village centres.
Route 6 inexplicably does not call at Wexham Park Hospital when it would be a 5 minute addition to the service, seems a spiteful decision when the route it replaced did. Route 12/13 is now a horribly compromised timetabling mess that will probably drive non-commuting passengers away from using the service. 10/11 and 15 used to be one route IIRC that went to Heathrow, it's now 2 unprofitable routes that are for the chop.
There doesn't seem to be a local publicity team anymore. Many of the route and fare changes in the last 2 years have been done without any useful publicity beforehand, no information was provided at most stops, so passengers have been left in the dark.
It is generally a challenging area to retain and recruit staff as there are plenty of easier jobs around Heathrow and traffic in the area is terrible. 