Hi all, I have recently moved to Aylesbury and my house overlooks Chiltern's maintenance depot at Aylesbury station. There are three class 121s that seem to be resident here. From what I can gather from the internet, there are two operational units that are regularly used in service, and one (ex ATW) class 121 that is supposedly used for spares. Thing is... The ex ATW unit is the only one that ever seems to move! Unfortunately I leave for work at 5am, and get home for about 6pm, so I don't actually see any of the movements of the units. The two 'operational' units always seem to be parked next to the maintenance depot behind some sort of diesel shunter, while the ex ATW unit seems to live in a siding next to the station along with another heritage DMU (which also seems to move often!). The ex ATW unit seems to be parked in a different spot in that siding each time I walk past. Does anyone know definitively what units are working, and when they work services?? Again the internet says they're used at peak times, but Chiltern's twitter guy said they only run lunchtime services?