I would start by saying that the service on the 850 is still better than Arriva, but it is becoming very poor in places, notably the peak hours. The 850 has some key functions, taking Wycombe and Marlow students to Henley College and taking Henley children to Marlow schools. These need the buses at these times to run and, where possible, be double deckers. I think Carousel has built up this market by running a better service and being more reliable than Arriva but is in danger of losing it again. In the new term the 7.45 from Henley to Wycombe has failed to run twice and been over half an hour late another day. Especially on Tuesday 8th when the following bus was a single decker. On some days the key buses from Wycombe to Henley have also been single deckers. There may be some logic to it but it seems almost random which workings get double deckers in some cases. During the day the position improves as buses come off other working but still journeys are missing and are late. Today, for example, the 8.30 to Reading was run by the incoming 36S due to arrive at 8.42. The 8.45 to Henley didn't track but may have run. No 9.00 to Reading.
There is a new school route to Henley College this term, the 623 from Cryers Hill via Amersham, the edge of Beaconsfield and western parts of Slough then Maidenhead. I don't think it has ever arrived within half an hour of its due time and typically up to an hour late. Today due 8.35, actual 9.21. That's no use for college students if they are expected to be there for 9.00! Usually a bit better in the evening but about 45 minutes late finishing its journey yesterday. Most of the other college service - the 607, 620, 624 and 625, don't track this term.
There may be driver issues but I think the problem is mainly shortage of vehicles. There are supposed to be 10 Streetdecks but one hasn't yet been out since repaint into the smart Riversider livery. Of the other nine only four are on the road today. No idea why. Five Scanias and two of the Flightline E400MMCs are off the road. None of these are long term. Caveat this, one double decker is probably on the 607. There are seven new second-hand Citaros but these do not seem to have been the most reliable buses - having said that all seven are out today.
There are also definitely traffic issues and I don't envy whoever has to deal with these. Some days it takes ages around Wycombe, sometimes in Marlow, Henley and Reading there can be severe traffic issues. You can't always predict where they will be but it is pretty certain there will be some. Notably they often don't allow enough time for a dead run to take up service, eg the 7.45 from Henley to Wycombe. This used to run off a 6.45 from Wycombe to Henley so you could see if it was tracking but now it comes into Henley via the A4130 and across the bridge which can have terrible traffic and only starts tracking when it picks up service.
I have never seen evidence of duplicate buses on the 850, I think this is most unlikely.
