There would not be a national ATO signalling system as the signalling/ATP is provided by ERTMS. This would not prevent interoperability as ERTMS would be used in all areas, the only difference is how the train is driven.
Isn't the plan for Thameslink is to overlay an ATO system on top of the ERTMS system? ATP signalling itself is generally insufficient to allow ATO, as an ATO box on a train can mis-read ATP indications on rare occasions, and can get confused if the train is diverted from it's pre-programmed paths due to delays etc. Thus, a central computer system monitors every train on the system, and by looking at the signals, timetables, speed of each train etc, this computer then tells the ATO equipment on board to change the speed of the train. This central computer interacts with the ATO boxes via trackside equipment. As there is no EU standard for ATO, the systems used in different countries is likely to be different preventing the ERTMS goal of inter-operability.
So is already in operation on the Victoria line then?
Yes, ATO has been in operation since the line opened in 1968! Central was next in 2001; Jubilee done a couple of months ago; and the Northern is planned by the end of 2014. The SSL (Metropolitan, Circle, Hammersmith & City, District) is likely to be at least partially ATO by 2020. It'll be interesting to see how they apply moving block ATO to the Met lines shared with Chiltern, if it goes ahead.
The one thing though is that I find the Vic-line ATO system uses the power and brake like on/off switches, travelled on one standing from signal to signal (or block to block more accurately I suppose) and rather than just taking a little bit of power to slowly drag up to the next signal block like a human driver would decide to do, it seems to go full throttle to the highest speed possible before braking hard again to stop - seriously one of the most uncomfortable rides I have ever been on!
Plus I am slightly biased I certainly do not want to be out of a job I bloody enjoy doing!
The original 1968 ATO system is pretty rough, due to the technology limitations of the era, but the newly installed system is a lot smoother. Still, it isn't as smooth as a human driver!
Don't DLR staff manually run trains on Sunday to keep their knowledge going?!
I don't know about the DLR, but the Central line drivers do operate trains manually on Sunday. Some Central line drivers also get practice by driving trains on the manual Waterloo & City line. Drivers on the Victoria line on the other hand, only get to drive manually in and out of the depot.