Well really the service is just an extension of the former Marylebone - Aylesbury via Wycombe service.
You guys are overexaggerating the delays!
Not necessarily so.
Whilst simple on paper by virtue of the fact that every timetable is (or should be) written to avoid conflicts and delay, once they do happen then the delays can escalate and quickly too.
Once a delayed service hits a 3-minute headway area with consecutive services, then the delays start to spiral.
The Aylesbury Vale Parkway service group is reasonably self contained, albeit with an interface with TfL services. The majority of knock onto other Chiltern services is otherwise confined to the Neasden South Junction to Marylebone route.
The section of railway between Bletchley and Milton Keynes, whilst small, can still have an effect on west coast services and then TfL services etc.
It's no exaggeration to say that delays can accumulate with such a small stretch of railway, which can frequently be the case at Tyseley and Small Heath.
There are of course ways of mitigating these, but has an effect on the customers and/or the operational performance of the railway.
