No - the train you liked to (4M42 22:08 Felixstowe to Garston)
is actually booked for a pair of 86/6s - for example, last night's
4M42 was worked by 86610 and 86639.
interesting how the 86's don't just take the Ditton train back to Ditton and infact go to Garston,
If you look at Ipswich yard:
http://www.opentraintimes.com/location/IPSWSS/2013-09-09/2200
You will see that the train from Ditton arrives
after both the Felixstowe
to Ditton trains (there are two within 20 minutes!) have departed, so the
86/6s return on the Garston train.
86 501 is a wild card - it can turn up on several different trains,
but 4L90 which I mentioned in a previous reply seems to be the
most common working at the moment.
All these trains traverse the GEML between 7pm and midnight,
so that's the time of day you need to be concentrating on...
MARK