"Paul Corfield" wrote in message
...

Also I'd struggle to understand how a slow running Met train would
really have any impact on Virgin Cross Country near Banbury given the
interworked LUL section really only impacts Marylebone - Aylesbury via
Amersham trains. Perhaps I'm missing something?

The problem lies in the fact that there are a number of tripback workings of
Class 168 'Chiltern Clubman' units between Marylebone and Aylesbury depot
following/prior to Birmingham, Stourbridge and Kidderminster workings. These
tripbacks are made as service trains on the Amersham route (plus a couple on
the High Wycombe route). Whilst the tripbacks *from* Marylebone will not be
a major issue, those *to* Marylebone from Aylesbury, in the early afternoon,
may cause delays on departure from Marylebone, due to short turnaround times
at Marylebone. For example, the 13:32 Aylesbury to Marylebone is booked to
arrive at 14:34 and then forms the 14:40 departure from Marylebone to
Stourbridge Junction. A late departure of this service and subsequent late
arrival at Aynho Junction, where the train drops into the cross-country
network, *could* cause a delay to a Virgin CrossCountry service.