Whilst Arriva were operating on the 685, the usual Carlisle vehicles were 11567 and 11568, the 2 E400MMCs.

Since the 685 has gone all Stagecoach, it as been quite common for one of these E400MMCs not to appear on the 685 but be used for various other services which typically includes a morning and afternoon schools run. It would appear that Carlisle have school runs requiring x double deckers and the decker allocation is x+1, so only 1 spare, hence an E400MMC gets reallocated - it will also cut down the daily mileage.  Note one of the 'school runs' is the 685 that goes through Hexham at schools in time and the same bus passes through Hexham at schools out time.

I had noticed that an E200 would now appear for the whole day on the 685.  But then some of the Carlisle Citi routes would be operated by E300s.

Also note that Newcastle now has a LEZ zone so any 685 bus going in to Newcastle bus station, needs to be LEZ compliant, e.g. Euro 6.